This is a difficult one. Not sure how to handle it without setting off WW3

[FuckOffAndWriteYourOwnArticles]

Bit of background: I am married to DH. We have two DCs who are 3 and 6. My SIL (DH’s sister) has a 2.5 year old DC by a married man who she is still having an affair with. To make it even worse, we very tenuously know the wife of the married man. One of the mums of a kid in my eldest DC’s class knows her. Oh, SIL and her DC live with MIL. MIL is widowed.

Okay, so the married man (MM) that SIL is having an affair with is going to be meeting SIL and her DC over at my MIL’s over Christmas for a secret ‘family’ get together. They’ve done this before but we’ve never had anything to do with it in the past. But this year SIL wants us to come over with our DCs so that the cousins can be together —and she can delude herself that she has a normal family—

I’d be uncomfortable about this anyway, because I find the whole thing a bit grubby. But what’s really pissed me off is that SIL said to DH that our DCs must be sworn to secrecy and can’t say anything about seeing MM at MIL’s house (because of the school mum connection).

I want to say a blanket ‘no way’ to the whole thing. My children are not going to be dragged into a dirty shagging lie. But DH is all ‘don’t be so judgemental’ and he and his mum are getting defensive of SIL and they think I’m implying his family are all Jeremy Kyle scum and I’m superior.

It’s all getting a bit political and I don’t know if I should just cave and agree to it because the DCs probably won’t even register MM and it’ll all be fine. AIBU to stick to my guns because of the principle? If I do, it’ll mean bad blood between me and MIL and also likely DH for a while.

I’d never get a child to lie or keep a secret like this.
It is grubby and very Jeremy Kyle.
As he isn’t really supporting her I’d stay well out of it with a vomiting bug to keep the peace.

And people who start trumpeting about how their own 'moral compass' entitles them to go barging in to a situation that isn't actually any of their fucking business

Bollocks to that, SGB. Most people are advocating the reverse, i.e. to keep right out of the situation rather than being drawn into condoning it and keeping secrets about it.

I have a friend who did not know he, his mom and his brother were his step dad's 'second', secret family. He knew he was his step child and brother was his natural child. He was 30 years old when his mum finally told him and his brother rather accidentally - because of some argument she had with said 'husband'. And suddenly it make sense why Dad was away so much, only dropped by shortly around Christmas...

This betrayal has wrecked his life. He is now over 40 and still not over it. It is not right of your SIL letting her kid grow up like that either not knowing, or knowing but being sworn to secrecy. This type of shit traumatizes people.

SGB your attitude to monogamy and alternative relationships is fine, but it doesnt make lying and cheating ok.

You can excuse it any way you like, but it doesnt change the facts.

He's not a catch though, is he? Because she hasn't caught. She's mother to the shameful little secret he sneaks off to see on a day squeezed in between Christmas and New Year.
If you end up going to this tell MM how awkward you find it and why. I guarantee it won't happen again.

I'm glad you and your husband have come to a sensible agreement. It doesn't sound like he's had a particularly good role model, if you've never had cause for concern over his moral judgement, I would put this down to family loyalty. Glad he escaped the cycle and hope you have a great Christmas. X

If being superior means not encouraging your kids to lie, and not being complicit with her lies, climb up on your throne and grab that crown.
Your kids can seen their cousins anytime so that incentive is bollocks.
She is living a lie. You don't have to.
If Your dh cannot see that what is being asked of you is unreasonable then he needs a fecking sharp wake up call.
I have never known a six year old to be able to keep quiet. Why insist on putting that pressure on them?
If your sil wants to live that way then fine but you want no part in it. Mil, mm and sil and your dh can do what they like but what a cracking demonstration of deceit to show the kids. Wow.

My point was more to the PP on the thread screaming that the OP should take it upon herself to tell the MM's wife because 'morality'. Which would be a really nasty and very unhelpful thing to do, because it wouldn't be OP who suffered, it would mostly be the kid.

Rights and wrongs aside (I’m firmly with you OP) the fuck I would allow anyone’s shitty decisions to impact my kids and worse than that, have them pressured to lie to keep a dirty secret (the affair is dirty, not the child).

Her mess, her problem, you’re spot on

ReanimatedSGB

Not just morality. The fact is, he has potentially exposed his wife to STIs. Not saying that SIL is part of the Great Unwashed or anything, but it's possible she picked something up from a previous partner and passed it on to him. Often STIs can have no symptoms.

My husband's ex had an affair before they separated. He was very upset that everyone seemed to know - and yet no one told him. The wife needs to know what her husband is doing so she can get herself tested and decide what to do about her marriage.

I agree with @SGB's point about telling people because "morality". You have no idea what trouble you could be unleashing for people who don't deserve it.

What ever happens your children have a cousin and it’s positive to build the relationship between them. I wouldn’t ask them to keep secrets. I would avoid being judgmental and aim to be kind.

Does he have children with his wife?