AIBU to not forgive SIL affair?

[Ambs81]

This is a complicated one- but I'll try to tell the short version! Any advice, especially from those who've experienced similar would be great.
Last year I found out a work colleague had split from their husband of 10 years after finding out he'd been having a 6 month affair with a younger women, who was known to my work colleague.
Like anyone, my work friend had completely broken down, she'd confronted the girl he was having the affair with -who she knew well and after a few days, rang the fiancee of the girl involved to make sure he also knew what had been going on.
She found out when typically, her idiot now-ex-husband had left his phone with hundreds of photos, video, messages from the other women in an archived chat. Most of it was quite sexual, but they had also told each other they loved each other, and discussed plans to leave their partners (talking solicitors for divorce, living arrrangements).
The plot thickened when a week later, it was mentioned in passing the name of the finance of the girl involved in the affair - it was my brother in laws name (my husband's brother). Its not a very common first name, or surname (now my surname), i was surprised my work friends hadn't already made the connection.
We quickly confirmed it was my BIL financee (they are due to get married this summer), I was shown some of the images / video involved and it was clear she was the guilty party, I also noticed she'd come off social media at this point.
I obviously told my husband, and explained his brother already knew what had gone on - but encouraged him to talk to his brother and support him through the fallout.
His brother was extremely upset we knew, and as his fiancee had managed to convince him the affair was just text messages, not sex, our input confirmed that it was sexual (i watched footage of them having sex!), which obviously caused my BIL more upset.
Long story short, 6 months later and my BIL has decided to stay with the his financee, after 2-3 days living apart, they decided they were both to blame and wanted to stay together.
My BIL suffers from depression, and it seems as though the family feel this caused her to have an affair, as he was distant and not meeting her needs. As someone who has suffered with depression, I feel really shocked that this is being used to justify her betrayal. Also worth noting she was my BIL first relationship/ girlfriend, so he has no other frame of reference.
They've also decided to go ahead with the wedding this year, 10 months after the affair came out. While I think it's far enough to stay together, I think going ahead with the wedding as planned is a joke - especially with it taking place in a catholic church.
While the rest of the family have totally forgiven and forgotten, my husband and I are really struggling to come to terms with it and treat her as family. My husbands family don't want it to be talked about, it is completely swept under the carpet now, but I havent directly spoken to my BIL or his fiancee since this came out (6 months ago).
At the request of my mother in law (who i greatly respect, she has helped me a lot with my DS) I did reach out to the girl involved, suggesting we meet and bury the hatchet. The reply was quite a rude and basically indicated they were angry at us, and that she was willing to accept me as family 'no matter what' (inferring I'd done something wrong??).
Since that exchange of messages there has been no contact, I'm avoiding family situations/ occasions where they'll be and visa versa.
I'm happy to continue with this, but with the wedding approaching i feel it is going to come to a head, as I don't want to attend and don't want my son to attend.
I would go out of respect for my BIL (who was a close childhood friend and how I met my husband), but as he hasn't spoken to me since this happened I feel that I have no relationship with the bride or groom, and it feels bizarre to think of going to their wedding when I'm not on speaking terms with them.
I still feel so angry at her and I feel devasted for my BIL, because he is such a lovely guy and I feel he is being duped. None of his close friends know the truth and I worry the only people he confinded in - his parents- were more worried about maintaining the status quo (as the wedding invites had gone out, they own a house together etc) then his self esteem and self worth.
As the family have moved on so quickly, I feel they think IABU to still hold a grudge and not let it go, I also know it will hurt my MIL and FIL to not have me at the wedding, more then anything because they wouldn't like their friends to think/know they was an issue/dispute in the family.
I know I'm taking the moral highground with nothing to really gain, but just can't move pass the fact that she did this to my BIL and also to my work friend - who has now ended her marriage of 10 years.
It seems wrong that on one side a marriage is over, but on the other its business as usual and the wedding planning is in full swing.
Had her cheating been a one off, or even a two-off thing, I wouldn't feel as strongly but it was such a prolonged affair, with meeting for sex 1-2 times a week in my BIL house, there was also a lot of bad mouthing of my BIL in the messages exchanged, and she was putting a lot of pressure on the man involved to get a solicitor and get a divorce.
I also find it weird that while my work friends marriage was in a bad place - they were having counselling - my BIL was unaware of any problem, and his fiancee seemed fine and very actively planning her wedding.
Another side note is my own brother, having cheated on his fiancee went ahead with his wedding and then split after 6 months - and still can't start divorce proceedings as haven't been married long enough. I wish I'd advised my brother to delay his wedding, but as he was the wrong-doer I guess I encouraged him (or at least didn't discourage hime) to make things right by going through with it (in the end it was his wife's choice to end it). I'm raising this as I have recent experience with how marrying of the back of infidelity is never a good idea!
Sorry for such a long post...I guess my question to you guys is AIBU to not forgive and forget, and AIBU to not attend wedding?

I would have a bad head that day and stay home. Don't let your ils make you a hypocrite - if you can't genuinely wish them well you can't really go imo.

Yanbu

I don’t particularly have any advice, just empathy. I recently found out my friend has cheated on her DH and I have lost quite a bit of respect for her, too.

Couldn't read and run but poor brother in law he deserves so much better

Also I would say you and your son have a sickness bug that day so you didn't not look like the bad one because clearly with or without you it's going ahead

I also wouldn't be able to watch and after reading that would like to smack her in the face I bloody hate cheating!!

Thanks - you've (already) made me feel less crazy!

Not your relationship so not your place to not forgive. If your BIL has forgiven and moved on then that should be the end of it. His life, his choice, he is a grown up.

He's a grownup and can make his own decisions. You really don't know what went on between them tbh.

Stay away because you're estranged, but not because you 'disapprove' of her. Be there, be happy for him and be ready to catch him if he's made a big mistake.

Agree with @dontlikebeards

My SIL had an affair. We made it clear we would support my brother in whatever decision he made. As that decision was to forgive her, we did as well.

It doesn't mean your BIL can't make a different decision at a later date, but it is his decision and it is not up to you to police his relationship.

Not your relationship so not your place to not forgive. If your BIL has forgiven and moved on then that should be the end of it. His life, his choice, he is a grown up.

^Rubbish. I would have no respect for people that cheat

Pulling out due to “sickness” will waste money, but it might be the most diplomatic option.

Yabu.

He’s forgiven her, they’re moving forward together. It’s not your place to forgive or not, it’s not you she’s betrayed and if the betrayed party can move forward then you need to as well.

You have no idea what goes on in someone else’s relationship, and bear in mind that if they have children etc those children will be family also.

I get the feelings against someone who can cheat on a partner but all this smug over investment and saying that you cannot forgive is just a bit much since you’re not the one who needs to be doing the forgiving.

YANBU

You are allowed to feel however you want about this, regardless of whether BIL has forgiven her.

I would feel the same as you, particularly when

they decided they were both to blame

That is so wrong, there is no excuse for what she did.

I think I am over-invested and I am angry at myself for caring so much.

I have a really big, extended family of my own to worry about so know I should let it go and focus on 'me and mine' as it were.

My SIL has totally moved on, truly doesn't care and is very actively involved in planning her Hen, and even planning a bonus-hen day, as the attendance for the planned hen weekend is really poor (a lot of her friends have cancelled, prob because they know or knew about the affair I'm guessing).

I am quite a anxious person and the thought of the wedding fills me with dread. My friend said just go and all you have to do is tell the bride she looks nice, eat your dinner and leave. But I don't think I could even do that.

Can 'hear' how conflicted and worried you feel about this but I'm struck that despite the relationship breaking down they have continued to what you to be a part of their day. Presumably they have made their peace with the Catholic Church and sort absolution. Can you not use the day to offer the same forgiveness even if you can't forget what has happened? It will undoubtedly have changed your thoughts unfortunately on both of them. It's rubbish that particularly your BiL seems to be 'shooting the messenger' but you are presently a reminder of something both need to move on from. Missing the wedding will miss being part of moving on and healing the wounds you all have by pledging to support their marriage. Otherwise this could fester for a very long time. You clearly care about your BiL - you may unfortunately be right that he will need you & you might feel better if you were part of making the marriage work for him than picking up the pieces after. For me it would be lippy on, smile fixed and raising a glass to the couple.

Why on God’s earth did you watch a video of them having sex? WTAF?

I don’t think you should do this. They are trying to move forward with their life and they have decided to stay together.

It really is none of your business and by taking the moral high ground you are actually causing further misery and pain to all those involved.

Go to the wedding, offer an olive branch before that.

Your BiL does not support your approach otherwise he would have been in touch.

You are causing issues.

YANBU what an absolute bitch. Your poor BIL. Unfortunately you can't do anything except support his piss poor choice. If you feel you have to, go to the wedding, but you don't have to stand there plastering a fake smile and I would leave early rather than 'celebrating' their farce I'd also tell anyone who noticed a vibe the truth. If she ever questions your attitude towards her, just say you can't look at her the same after seeing the videos of her in action.

It's a mistake, but it's his mistake to make.

I suspect a lot of people have cancelled from the hen because they don't want to spend a lot of money (and probably sub the Hen) for a wedding that is only going to last a couple of months at best.

For the sake of family harmony I'd go, avoid the couple in question (just smile and nod in their direction) and leave. You don't have to actually participate (say you don't feel well or something for the photos), but it might be important for your BIL to feel supported in his decision to stay with her.

YABU - not your relationship, not your place to forgive. At a time when BIL needed support, you managed to alienate him. And you do not know the ins and outs of a relationship. There are things about my relationship that absolutely nobody knows no matter how close they are. Out of embarassment, out of guilt, there’s all kinds of reasons why your BIL is keeping some things quiet.

Also, your SIL is not to blame for breaking up your colleague’s marriage, that was her husband.

Yes she's a bitch.
But why do you feel that way? Because you sympathise with him.

But you and your husbands attitude will not be helping your BIL - in fact, it won't help him heal at all. Your known hatred just adds a new dimension to this whole ordeal. Who's to say this whole thing has given your SIL a wake up call? It happens!

A previous poster is right - you're causing issues and hurt where it's not needed. Nothing is black and white, affairs happen, sadly, but your attitude can resulting in your BIL resenting YOU.

It's not your place to judge when he has made his decision. You don't know the full story whether you think you do or not. For all you know he could've been doing exactly the same thing and is just as guilty.

Other people's dirty laundry is not yours. Remember that.

Thanks all - mixed opinions but I take it all on board.

Re; the wedding, what makes it worse is that most of my BIL friends are also my old school friends, that he has remained very close to. So i feel if I was there but acting strangely...it would be more noticeable (if that makes sense??)
Other side note, the wedding is on a Wednesday so likely to be a fairly low key one (i presume??)
I could easily get away with not drinking due to work, etc

I think it's harder for you to forgive than all his family because you've seen the pain it has caused your work colleague.

I wouldn't be going to the wedding either

No. No way would I go.

I would find it all difficult enough re the afair itself. But the fact that she had the fucking gall to text you like that? She will accept you as family? WTF?!

After that exchange, not only would I not be going but I know that there is no way you'd get my DH there either. No way.

Both of us would be of the opinion that if she feels that high-handed about the whole thing and clearly has not an ounce of shame - she can feel the fucking burn on her wedding day and know PRECISELY why her new inlaws arent attending. Bring it on.

I'd actually have a fair bit of trouble convincing my DH not to quite happily blab to whichever friends of BIL are within earshot exactly why we weren't going either. Not because he's a bastard but because I think he'd happily take the flak in exchange for letting BIL's mates know what the score is. Quite frankly, although BIL sounds like he's handled this extremely poorly, he also sounds a real victim in this and yes, I'd be worried that he's making a huge mistake.

So if you can, tell some of his closest friends. A wedding is a bloody expensive mistake.

Does MIL know how she replied to you? Because I would consider explaining it to her. You have respect for her - it needs to go two ways. Let her know what that fucking horrible woman is like, and explain that there's only so much she can ask of you. And maybe say that divorce within a year is perhaps the most embarrassing option of all.