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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

To be really disgusted with SIL's behaviour

128 replies

itsgoodtobehome · 01/07/2025 15:14

I'll start off by confirming the usual MN response - yes, I really don't like my SIL. She has pulled so much crap over the years that I have known her, that I really dislike her. However, I have always held my tongue and tolerated her. We have now had an incident that might have just tipped me over the edge, but the thing is, it doesn't really affect me. It's just another example of her entitled, spoilt and narcissistic behaviour which makes me really not want to have anything more to do with her.

SIL is single. Never been married, never had kids. She has however, been having a 'relationship' with a married man for the best part of 20 years. They had been dating, but he then decided that he wanted to marry someone that wasn't her. But rather than end things with SIL, he decided to keep her as his bit on the side, and she was happy to go along with that. He gave her the usual spiel - he married the wrong person, he didn't really want to be with his wife, he was going to leave but needed to wait until the kids were older, etc etc. This went on for 20 odd years, with her taking the scraps offered to her and waiting for the magical moment when he would leave his wife. Finally that moment came. Only problem is, it wasn't SIL that he left for, it was some other poor sucker who had also fallen for the same story. No idea how many others there may have been.

SIL is now beside herself. Posting all over social media about how she has been let down, betrayed, she's going through a trauma etc. Totally playing the victim. In my view, this was completely predictable and she is just as much to blame as him. Hasn't given a second thought about the wife and kids that are the true victims in all of this.

Like I said, this really has no impact on me, but I am just so sick of her 'poor me' behaviour and am finding it really hard to have any sympathy whatsoever, and it's just generally left me feeling quite sick that she has such a low moral compass. I just really don't want to have to engage with her any more, but if I give my reasons, does it just sound like I am being judgemental?

YABU: It's got nothing to do with you and you should just let it rise above you and not judge
YANBU: This is really disgusting behaviour and you are perfectly within your rights to not wish to engage with a person with such a low moral compass and has been a pita the whole time you have known her

OP posts:
GintyM · 01/07/2025 19:28

YANBU at all. She knew exactly what she was involved in for years and still went along with it. Now acting blindsided is just ridiculous. Honestly, it’s hard to watch someone cause that much hurt and still expect sympathy. No one would blame you for wanting to step back.

User37482 · 01/07/2025 19:30

I think she’s been foolish more than anything, some men lie very well and some women want to believe the lies. I kind of feel sorry for her,

Rosscameasdoody · 01/07/2025 19:32

User37482 · 01/07/2025 19:30

I think she’s been foolish more than anything, some men lie very well and some women want to believe the lies. I kind of feel sorry for her,

As far as I can see the only lie was telling her he would leave his wife for her. SiL was the OW right from the start - even after him dumping her to marry someone else. That, plus the fact that he was spinning the line for over twenty years should really have told her everything she needed to know.

Ihatelittlefriendsusan · 01/07/2025 19:34

Convenient that you now claim not to have known about a 20 year relationship once called out and therefore not having the moral highground. Pretty big thing to leave out of the OP.

Yabu and you know it.

Rosscameasdoody · 01/07/2025 19:35

ilovesooty · 01/07/2025 18:08

I said "understand that" (ie her response to the situation) not "understand her".

Anyway it appears that some posters are as devoid of imagination and compassion as the OP is.

Compassion for who ? The SiL who knowingly involved herself with a married man right from the start of his marriage ? Or the wife and children who will now be devastated and even more so when the extent of his cheating inevitably comes out ? I know where my compassion lies and it’s not with a woman who sets such a low bar for herself and is surprised when she’s treated like dirt.

Rosscameasdoody · 01/07/2025 19:36

Ihatelittlefriendsusan · 01/07/2025 19:34

Convenient that you now claim not to have known about a 20 year relationship once called out and therefore not having the moral highground. Pretty big thing to leave out of the OP.

Yabu and you know it.

I have trouble with this too. I just don’t see how this could have been covered up for twenty years.

R0setheHat · 01/07/2025 19:38

Ihatelittlefriendsusan · 01/07/2025 19:34

Convenient that you now claim not to have known about a 20 year relationship once called out and therefore not having the moral highground. Pretty big thing to leave out of the OP.

Yabu and you know it.

i don’t believe that but even if she had known about it for 20 years what should she have done?

Rosscameasdoody · 01/07/2025 19:39

ThisPlumZebra · 01/07/2025 16:17

Totally get it, you’ve bitten your tongue for years, and this might just be the final straw. It’s not about being judgemental, it’s about having boundaries. Her behaviour is awful, and it’s okay to step back from someone whose choices constantly make you uncomfortable. You don’t owe her your time or energy just because she’s family.

OP updated that she didn’t know about the affair until it ended.

ilovesooty · 01/07/2025 19:39

Rosscameasdoody · 01/07/2025 19:35

Compassion for who ? The SiL who knowingly involved herself with a married man right from the start of his marriage ? Or the wife and children who will now be devastated and even more so when the extent of his cheating inevitably comes out ? I know where my compassion lies and it’s not with a woman who sets such a low bar for herself and is surprised when she’s treated like dirt.

You're entitled to your opinion. As am I.

IberianBlackout · 01/07/2025 19:41

YANBU but some women enjoy being the OW, she’s only upset because she’s not as special as she thought she was.

I recently found out the boyfriend of a woman I know (SIL’s close friend) is actually a married man. She’s beautiful, successful, hard working… and this is what she decided she was worth?

But then DB and SIL started having problems, separated and she kept showing up there at all sorts of times right off the bat and knowing full well they were working on it. So the only conclusion is that she seeks committed men because it gives her some sort of validation.

Ihatelittlefriendsusan · 01/07/2025 19:43

Rosscameasdoody · 01/07/2025 19:39

OP updated that she didn’t know about the affair until it ended.

Nothing. But she doesn't get the right to be the moral judge now

sandyhappypeople · 01/07/2025 19:44

Rosscameasdoody · 01/07/2025 19:36

I have trouble with this too. I just don’t see how this could have been covered up for twenty years.

Exactly, there is no way on earth someone who has kept a relationship secret for 20 years from everyone in their family (is that even possible), would randomly post about it all on social media to say how hard done to they are and expect everyone to commiserate with her over it after it ends.. commiserate on a relationship that she never ever mentioned to anyone ever for 20 years and expect family to be supportive?

Doesn't sound plausible at all to be honest.

None of OPs business though clearly.

User37482 · 01/07/2025 19:46

Rosscameasdoody · 01/07/2025 19:32

As far as I can see the only lie was telling her he would leave his wife for her. SiL was the OW right from the start - even after him dumping her to marry someone else. That, plus the fact that he was spinning the line for over twenty years should really have told her everything she needed to know.

Edited

Yeah she believed him because she wanted to. If someone I was seeing married someone else I would see that a pretty big red flag. She’s a fool no doubt about that. But people can be weird, how many people are tricked by on-line love scams that are clearly scams or fall for the “she doesn’t understand me” line. I don’t think she’s more to blame than him tbh. She’s not married to anyone, he’s the one who owes his wife fidelity, she’s just wasted decades of her own life.

I know who i would blame if DH cheated on me, definitely DH, random women have never made any promises to me. DH did.

User37482 · 01/07/2025 19:48

IberianBlackout · 01/07/2025 19:41

YANBU but some women enjoy being the OW, she’s only upset because she’s not as special as she thought she was.

I recently found out the boyfriend of a woman I know (SIL’s close friend) is actually a married man. She’s beautiful, successful, hard working… and this is what she decided she was worth?

But then DB and SIL started having problems, separated and she kept showing up there at all sorts of times right off the bat and knowing full well they were working on it. So the only conclusion is that she seeks committed men because it gives her some sort of validation.

Probably a bit more exciting than a full time proper boyfriend. Bit like a kink imo.

DontReplyIWillLie · 01/07/2025 19:52

Rosscameasdoody · 01/07/2025 19:39

OP updated that she didn’t know about the affair until it ended.

Which she drip-fed a few posts in. When she’d described the current twist as “the final straw”. It’s not too surprising that people assumed there were several other straws - the main one being the affair.

lighthouseahoy · 01/07/2025 19:56

You sound quite unkind. She's never married and had kids because she's been used and future faked by this horrible man. As what what she "deserves" she's paid a hell of a price for her poor judgement.

IberianBlackout · 01/07/2025 20:00

@lighthouseahoy presumably if you’re an adult when you step into an OW role, you’re not really being used or future faked. You know what’s up.

If anything, his family was future faked.

R0setheHat · 01/07/2025 20:03

Ihatelittlefriendsusan · 01/07/2025 19:43

Nothing. But she doesn't get the right to be the moral judge now

Okay… pretty sure it makes no difference, the OP clearly hasn’t condoned it for 20 years. Your posts don’t make much sense and you replied to the wrong reply. Just sounds like you’re weirdly bitter about something

cocoromo · 01/07/2025 20:05

Just keep things as they are for the sake of your husband. Unfollow her on SM

lighthouseahoy · 01/07/2025 20:07

IberianBlackout · 01/07/2025 20:00

@lighthouseahoy presumably if you’re an adult when you step into an OW role, you’re not really being used or future faked. You know what’s up.

If anything, his family was future faked.

He was dating SIL first, told her he shouldn't have married his wife and was going to leave when the kids were older. I'd certainly say he spun her a line and promised a future he had no intention of delivering.

I don't think she has behaved well by any stretch of the imagination but presumably she is now too old for kids and has wasted decades on this man who had no intention of delivering what he promised. I'd say that she's paid a very high price indeed for her stupidity.

sidetosidebackwards · 01/07/2025 20:17

@IberianBlackout
So the only conclusion is that she seeks committed men because it gives her some sort of validation.

Not necessarily. Some women get involve in affairs because they are basically commitment phobic and it suits them to have a pseudo-partner - someone to have sex and excitement of illicit encounters with, without having the bother of meeting a mother-in-law and dealing with his filthy habits of leaving clothes on the floor. Affairs are usually the lust filled excitement of relationship early days stretched out becuase of secrecy with none of the mundanity of real life. It's all sexy unwear, hotels, champagne and nice restaurants.

It's not good behaviour and I'm not condoning it - just saying that it isn't necessarily a self-esteem or a validation issue. For some women, it's because they want some bits of a relationship but at very arms length.

I've known more than one woman like this and they were very successful professionally, very high powered and not interested in settling down and averse to commitment. It's almost at the point where if I meet a woman who is on the surface long term single but you look at them and think ' you have everything - you look great, great job, fabulous lifestyle why have you been single for so long', it almost always turns out they aren't quite single.

BunfightBetty · 01/07/2025 20:17

Beak out, OP. It’s not for you to judge SIL and try and enact some sort of punishment to rub her nose in it. Unless you yourself are so virtuous you have never ever done anything shitty and therefore can confidently claim the moral high ground?

You’re not the injured party here, so don’t get involved.

Just be civil when you see her for your DH’s sake, and don’t try and take a major part in her drama. Not your circus, not your monkeys.

itsgoodtobehome · 01/07/2025 20:18

DiamondThrone · 01/07/2025 19:03

I do wonder about this. How can you keep a relationship under wraps for 20 years?!

Did she say she was dating, or was happy being single, or what?

Was she dating? Or just hanging around for this prince?

She did date. She used dating apps but was never happy with anyone she met. It's obvious why now - none of them matched up to Mr Prince. She would sometimes hint that there was somebody on the scene and all would be revealed soon, but that never happened. So I just assumed she was having a few relationships that never came to anything.

OP posts:
joliefolle · 01/07/2025 20:24

So, this woman did not start an affair with a married father. She was dating him, he then started a relationship with someone else, married someone else, had kids with someone else, all the while maintaining a relationship with the woman he was dating, this went on for 20 years and at no point did she find the self-worth to to stop, as you say OP, accepting the scraps he offered her. You say she is narcissistic. Yes, narcissism is a huge defence against deep self-loathing. You don't have to like her. You don't have to condone infidelity. You don't have to be her friend. But if you are dreading having to see her next time etc. maybe you can try to dig deep into yourself and think about why she is like this, why her life is so fucked up. It doesn't just come from nowhere. The fact that she is incapable of empathy doesn't mean that you should just switch your own capacity for empathy (not sympathy) off. That is, of course, assuming you yourself are capable of empathy.

Discofish · 01/07/2025 20:38

I think you're enjoying an excuse to have a rant about someone you don’t like- and enjoying taking the moral high ground.