How to deal with my sister in law?- Advice needed

I’m a 27-year-old woman. My brother got married three years ago—to the person I hate the most. Let me explain why.
It started like this: her father is a good friend of my father, I believe. My sister-in-law’s mother is a very cunning woman she doesn’t even let her husband talk to his own siblings. Now, about my sister-in-law (let’s call her B).
B got admitted to the same university I was already attending. She’s older than me but is a Hafiz-e-Quran, so her mother forced her to take a two-year break from school. Her mother wanted me to take her to university with me. I said yes, of course we were family friends, after all.
At that time, my brother noticed her. She used to make these weird gestures around him for example, whenever he handed her something like her bag, she’d touch his hands. She seemed so sweet back then, I swear. Now I know it was all an act.
I graduated, and my brothers and I were already living in a different city for work. She knew that. After their marriage which we went all out for, since it was the first wedding in our family we lived in an apartment. She already knew I couldn’t just leave that apartment because I had a job. But I gave them so much space. I’d come home at 5 PM and then go to my cousin’s place. I even told them not to worry about me, and to let me know if their privacy was being disturbed I’d take care of it.
Keep in mind: it was my parents’ apartment, which they got because of me. And I contributed to everything from groceries to snacks.
Suddenly, three weeks into the marriage, B started acting out. One day she just stopped talking to me. I asked, “Are you okay? Is everything alright?” She didn’t reply. So I stopped talking to her too.
She used to scream at my brother all day and talk badly about me and my parents. One time, she threw a lamp at him. I heard the noise. My brother rushed out of the apartment. Later, I heard crying, so I went to her and asked, “Is everything okay? Do you need water or something?” I brought her a glass of water I was genuinely scared. She shouted at me that she wanted a divorce and told me to tell my mother. I said okay and told her to calm down.
At that moment, my brother came back and told me to move away from her because he was afraid she might hit me too.
The reason for that fight? She didn’t like my brother talking to me not even for a second. She blocked me from his accounts and blocked my number. Whenever we spoke about something important, she’d secretly listen, as if we were doing something wrong -Astaghfirullah.
I started ignoring her existence, and that irritated her too. What else could I do? I didn’t like being disrespected. She used to check my room when I was out. She started buying whatever I had I noticed this gradually.
Then came my own engagement and marriage. My wedding was planned for about seven months away, and she annoyed me relentlessly. Mind you, I never once said anything to her. My brother noticed and would talk to her privately, but she wouldn’t listen. She always asked for a divorce. My brother told my parents and her that he wanted to wait until after my wedding because in our culture, you can’t have things falling apart three months before a wedding.
Then B’s mother got involved. She told her daughter, “If you get pregnant, he’ll never leave you. And after the baby, you can blackmail him with the child.” How do I know this? Because B indirectly told me herself while we were having tea one day.
I was busy with my wedding preparations. In my last two weeks at that apartment which was indirectly mine too, given how much I contributed, and I now regret it she made my life hell. I used to cry when I was alone. I eventually left and started staying at my aunt’s house because they told me not to go back where B was. They were scared for me.
I got married. A few days later, she became pregnant. I was truly happy for her I called to congratulate her. Then I moved abroad.
One day, she messaged me saying, “Stop talking to my husband.” And she sent me screenshots from our conversations from 6–7 years ago. In those chats, my brother and I were joking about his potential future wife, just teasing. We had a great bond. I used to say things like, “You’ll be such a desperate husband because no girl even asks about you.” Mind you, B wasn’t even in the picture then. There was no girl. I was just teasing my brother.
She sent me those screenshots and said, “Get out of our lives. Why did you talk to my husband like this?” She also said she’d talk to my husband about it.
For the first time, I replied: “Act like educated people. You’ve annoyed me enough. I won’t tolerate any more.” I told her to go ahead and talk to my husband. Then I told my husband everything he supported me fully. I called my brother and told him everything, and my parents too. Then I blocked her everywhere.
When I went back to Pakistan, I didn’t talk to her. She called my mom and complained that I had blocked her. My mom told me to “be the bigger person” and unblock her. I did. But when I met her, I didn’t talk to her properly I just couldn’t after everything.
Right before she gave birth, she told my brother to invite me to lunch. My brother forced me, so I went. During those two months I was in Pakistan, she didn’t let my brother meet me. He only called me when she wasn’t around he still does that. He always says he feels stuck in this marriage because she’s pregnant (and now because of the child), and he doesn’t want his child to suffer because of her.
Now the baby is here. We were all happy truly. I love my nephew to death. But she started having episodes again. This time, she warned my brother that she would hurt the child if he ever talks to me. She doesn’t let me talk to my nephew. I always ask for pictures and videos, but she doesn’t send them. My brother shares them secretly.
The other day, my brother literally cried. He said, “I’m living with a devil.” She curses him, tells him he doesn’t deserve to live. It boiled my blood how can she curse the man who has tolerated all her tantrums and never says anything back?
To this day, she hates me. I don’t even know why. I only talk to her occasionally because I love my nephew and I want to be in his life not in a bad way, just as his good aunt. I just want to be close to him idk what do I do at this point.
Thanks for listening to my rant, everyone.
#sister in law, #brother #family