'AITA for 'protecting' my SIL who cheated on my brother and 'interfering' in their marriage?'

'AITA for 'protecting' my SIL who cheated on my brother?'

2 years ago, our family was caught in a huge drama. My SIL had a month-long affair with someone from her night courses. At that time, my brother was absolutely destroyed, and he wanted to divorce her. It was hell for almost 3 months, but he ultimately decided to stay married to her and work through it in counseling.

I wasn’t a fan of that idea, but it’s his life. I think he stayed mostly for their kid. But I honestly think it’s been terrible for him. Since then, everything has been miserable. My parents openly hate her now. She has stopped coming to family meetings because it’s outright hostile to her. Their kid still comes around, but my mother often bad-mouths her in front of him. He’s only 3, and it’s confusing for him.

My brother and I went on a road trip recently to pick up our grandmother and bring her to my parents' house for the holidays. It was 4 hours there and 4 hours back. During the drive, he started talking about the rules they have in their marriage now.

Here’s what he told me: SIL has to come straight home after work. She can only go out if he’s with her. He inspects her phone every few days and can do surprise checks. She had to cut off all her friends and can only have new ones if he approves them.

She has tracking apps on her phone and AirTags on her car, purse, and even in her running shoes. She does all the housework. Meanwhile, he has given himself a free pass to sleep with other people.

I couldn’t believe what I was hearing. I told him it sounded like he was punishing her, not rebuilding their marriage. He shrugged it off and said she deserved it for what she did. I asked him if he even loved her anymore or if he hated her. Because from what he was describing, it sounded like he stayed married just to make her life miserable.

He got defensive and told me I didn’t understand what it was like to be cheated on. But I do. I’ve been cheated on, and it was devastating. I separated, and now I’m happy because I didn’t want to live in misery with someone I couldn’t trust. I told him he wasn’t just making her miserable, he was making himself miserable, too.

He’s poisoning everything for both of them, and their child will be stuck in the middle. I asked him if he would prefer to separate, co-parent, and move on to find someone he could actually trust. I said it would be better than living in this constant resentment. He didn’t want to hear it and said I should mind my business.

When we got to my parents’ house, I asked to speak with my SIL privately. I wanted to see if she was okay because this sounded awful. She broke down crying and admitted she feels trapped but is staying for their son. She begged me not to tell anyone, so I promised I wouldn’t.

Later, my brother found out we had talked, and he got furious. He accused me of protecting her and interfering in his marriage. My parents agreed with him and said I should have stayed out of it. They think she deserves everything she’s getting for what she did.

I feel like this is so toxic for everyone involved. No one deserves to live like this, not even someone who made a bad choice/decision. Their son is growing up in the middle of this disaster. I just don’t see how this is good for anyone. Am I in the wrong for saying something? Should I have stayed out of it?

What do you think? AITA? This is what top commenters had to say:

Bencil_McPrush said:

If you think children of divorce have it bad, wait till you meet the children of will-you-please-and-for-the-love-of-God-get-a-divorce! That poor kid's gonna need therapy til he/she's 60.

Gator-bro said:

The damage to child will be off the charts. They need a divorce and therapy

InevitableDiamond364 said:

Both are idiots . She could also ask for divorce and move on . This way all the lil son learns is what mistrust , resentment, hate in a relationship means . And you are right he is also punishing himself . He rather live in hate then moving on and find peace and happiness and his hate will follow their son life .We all know that parents are the main cause of all the trauma in the adult life.

Everyone who goes to therapy figures out that their issues lie mostly in their childhood . And your parents also add to the boys conflicted view of women . How will the boy respect women when all he sees is they deserve to be punished and even when you don't fight in front of the kids , enough studies showed that kids can feel the thick air.

He is destroying his son by staying in this environment but yeah let's live in the illusion that living with a person you hate is better for the child than living in peaceful households

OP responded:

Yeah she def could. But she is also a coward. Or else she would not have cheated.However i do not know how safe my brother is atm. It would not surprise me if he had held something over her head. Like child custody or something like that. She would not say more but hinted strongly at that. But i don't think i can quite believe either of them. They should just end things

And ThrowRArosecolor said:

NTA. Has your brother always been abusive to her or is this a new thing? Your brother is behaving terribly and his justification is bullsh!t. He now seems to have an indentured servant and he can cheat on her whenever he likes…… you know, that thing that was so terrible that he imposed all these rules on her.

Tell your parents all the rules he now has for his wife. If they still think you’re the bad guy, I hate to say it but maybe your parents are also not great people. I feel bad for your SIL and I would help her to leave the marriage.

OP later shared this edit with some more info.:

I’ve read some of the responses, and I see that many people believe my SIL deserves this because she cheated. I understand why people feel that way. Cheating is not a simple mistake.

It is a deliberate series of decisions someone makes, knowing full well the harm it will cause. It is a betrayal of trust and a violation of the foundation of a relationship. What my SIL did was completely wrong, and the pain she caused my brother is undeniable.

Even when we acknowledge how serious her actions were, I think it is important to ask whether the response is proportionate. At what point does holding someone accountable for their actions cross the line into punishment that goes too far?

Is it justified to control every aspect of someone’s life indefinitely because of their betrayal? Does one series of terrible decisions mean they deserve to lose their autonomy and live under constant surveillance?

Punishment and accountability are not the same. Punishment focuses on revenge and making someone suffer. Accountability is about addressing the harm, rebuilding trust, and creating space for healing. What my brother is doing feels much more like punishment than accountability.

There is a difference between healthy boundaries and excessive control. Healthy boundaries might include open communication, setting clear expectations, and working together to rebuild trust. What my brother has done is create a dynamic where one person has all the power and the other has none. That is not healing, and it is not a foundation for a strong relationship. It is a cycle of resentment and control.

When I was cheated on, I did a lot of thinking. At first, I wanted my ex-partner to suffer. I fantasized about revenge every day. I would make up scenarios in my head about ways to sabotage his life and make him as miserable as I was. But the truth is, I was the one who was miserable.

Holding onto that anger only hurt me more. Letting go did not mean forgiving my ex or saying what he did was okay, but it allowed me to move on and focus on building a better future for myself.

If my brother truly cannot forgive my SIL, that is his right. But staying in this marriage just to punish her is not helping him heal. It is keeping him in the same pain and resentment I felt. It is not just affecting her. It is affecting him, their child, and everyone around them.

This is not accountability, and it is not about rebuilding trust. It is about control, and it is creating an environment of anger and bitterness that helps no one.

I ask again: where is the line? At what point does addressing harm become a way to perpetuate it? Does anyone truly benefit from living in this kind of misery? If my brother wants to move forward, whether with her or without her, he needs to think about what that looks like in a way that actually heals instead of keeping everyone stuck in the past.