'AITA for ditching a family get-together after my sister's husband blamed me for his affair?'

"AITA? My (f29) sisters (f43) husband (m50-ish) blamed me for his 2 long year affair."

For a bit of context; I already had a rocky relationship with my family, particularly my mother (f63) and this sister. So my sister (let’s call her Rose) married this guy (Jeff) several years ago. A couple of years ago, Rose started receiving messages from a burner Instagram account saying her husband was cheating on her.

She brushed it off for a long time thinking it was just some troll, and carried on with her life, happily married. Then, several months ago I got a phone call from my mother where she began the conversation with “how long have you know about Jeff’s affair?!”

After I denied any knowledge she explained that Jeff had told Rose about his affair and that the woman was threatening to ruin his marriage. The woman claimed that she and I were really close friends, and I knew everything about their affair and could ruin my sister’s life with the intel I had fed her.

She alleged that she knew me because I was blackmailing one of her friends (?) and she was one of the people warning me off, but somehow this has turned into a friendship where I tell her all my sisters secrets.

As my mother was clearly going to ring my sister straight after her call with me (it’s her usual form), I explained I knew nothing about it, and if I had I would have told Rose in an instant. Then carried on with my day, but remained stressed about it.

I was updated in drips and drabs by my mother for the next few days, and finally received a text from Rose saying that there was some stuff being said about me and that I needed to sort it out. Then she blocked my number and deleted me from everything.

So, at the end of my work day I rang her to straighten things out, and she began the conversation by saying that she was my big sister and no matter what I’ve done she’ll never judge me and will always be there for me. Which was sweet, but entirely misguided. So, I explained the same to her as I did to my mother.

She seemed to accept my explanation, and I told her that if she needed anything she could come to me but I would give her time to sort her marriage out if she’d prefer. I haven’t heard from her since.

Since then, asides from a brief period of contact when my step dad was in hospital, and a couple of texts updating me on big family things (ie deaths etc), I haven’t had any contact with my mother either.

Last night, I got a phone call from Jeff while at a friend’s birthday party. He asked if I was going to my mother’s for a family get-together, I said no, and he actually dared to ask me why. I explained that I was at a friend's, so I didn’t want to get into it right then, but there were a myriad of reasons that he was aware of. He then said he’d call me today, and hasn’t.

While I don’t feel guilty for not going home to see my family, I know they will try to make me feel bad, so basically yeah, AITA?

She added some clarifying info. in the comments:

Just to clarify I don’t know this woman, thus wasn’t feeding her info about my sister. He claims he couldn’t stop the affair sooner because this woman was saying she could ruin my sisters life with stuff I had told her.

My mother is a lunatic and will instigate a fight whenever she can, and has with others at previous family holidays, but ultimately my step dad, other sister, and niece / nephews had nothing to do with it so I feel bad for not seeing them.

What do you think? AITA? This is what commenters had to say, plus OP's responses:

s-nicolexo said:

So, your BIL is cheating on your sister, with your friend? Your friend reached out to your sister Your sister chose to stay Everyone is mad at you? Is that right? NTA

OP responded:

He cheated with his therapist who is a woman I don’t know, but claims to know me (word count meant I had to leave some details out), but yes they’re mad at me. My family expects everyone to forget things and carry on

Ok_Job_9417 said:

NTA - the only person responsible for the affair is the person having the affair. It doesn’t matter if you knew, didn’t know, threats or whatever. The husband is the one who decided to cross the line and fall into someone else’s bed.

daddysxenogirl said:

Wut? you already weren't going there when he asked. So do you even know the girl he was sleeping with? How does this equate to him blaming you for his affair? I need info to make any sense of this.

OP reponded:

I would have gone to the family get together, were it not for this drama, because I just dont think I can face him. I didn’t know the girl, but she said she did know me and I was feeding her info on my sister.

He told my sister that the reason he couldn’t stop the affair sooner was because this woman was holding information about my sister over his head, that I had allegedly told her.

mysteresc said:

NTA, I think. Are you not going home because Rose and Jeff will be there, and you want to avoid a confrontation? Or are you not going because you made other plans? Or is there another reason for not going?

And OP responded:

It’s a mix of the Rose and Jeff situation, and my mother’s addiction for drama. I felt like she made the situation worse with her response and not allowing me to contact Rose. My family are drama addicts, and tend to hold grudges while expecting others to just get over things. It’s a mess.

However, I would like to see my step dad, my other sister, and my niece (16) and nephews (9&12) as none of this is their fault, but I just know that if I visit on a day when my whole family is all there together, it’ll all blow up.

And Cherry_clafoutis said:

Realistically, the most obvious person to be sending the messages is the mistress. It has been two years of being the dirty secret and she has decided it is time for Rose to go so she can be the next Mrs Cheating-AH. Personally, I think she deserves him. It always nice when two awful people find each other and focus all that awfulness on each other. It is a shame Rose is collateral damage.

What I don't understand is why your family would believe you would be gossiping about Rose's cheating husband behind her back instead of telling her when they have known you all your life and while the mistress has shown themselves to be manipulative, completely unethical, has a huge incentive to break up Jeff's marriage but doesn't want Jeff to blame her for the marriage breakdown. NTA.