my sister in law (20F) and i (21F) used to be like best friends. her and my brother (24M) got married like nine months ago. we got into this big argument the week of their wedding and our friendship hasn’t been the same since.

we still talked and did stuff together but every interaction was like walking around on eggshells. if you didn't agree with her then she's pissed. if you did something that she didn't like or would never do herself then you're weird. if you like things she didn't like then you're weird. it was like no matter what everything had to be her way or no way at all--given it may have always been like that but i didn't realize it until after our fight. (Given i’m also a big believer of not letting one misunderstanding ruin a friendship so i tried to put our initial fight behind us and be friends)

Recently (we work together) some coworkers pointed out that she was flirting with some coworkers. ( also important to point out: it's the kind of thing if only one person told me then i would've brushed it off but i had multiple people coming to me so i started watching harder.) at first it was little things. staying too long in the back of the store, giggling too loud, standing too close...but then there was the being able to tell two of them were texting back and forth while standing right beside each other...then came the defensiveness and over explanations of why they were talking. so i talked with some of my closest friends about it.

Most of them said that i should talk to my brother about it and tell him my concerns because “having sex isn’t the only form of cheating”- which i 100% believe. you shouldn’t be give other people you’re attention when in a relationship( and i mean this in a “you shouldn’t flirt with other people or talk ill of your spouse to other people in a way to grab their attention- which she did)

anyways it got back to her that i thought she could be cheating on my brother and it blew up into this big thing. i told my brother about it and she denied denied denied. now she quite literally hates my guts. goes out of her way to try to make me have a bad shift at work. screams at me and cusses me out. talks about me behind my back. posts about me all over social media talking about betrayal and mistrust. you know the whole shebang...so AITA?