I need help and opinions from mommies! Pregnant or not !

I need help. I know at the end of the day it is my choice but I just need other ladies opinions. It's going to be long... just please take the time and help..

My sister is 18 years old and she just got engaged to this horrible guy. (I've known him for years and he's just gotten worse.) For example, he has threatened my life, been on drugs for years while he has had his year old son, he overdosed in my brothers apartment on heroine and almost made my brother go to jail,he's controlled her from hanging out with me to what she wears, and so much more. I'm 9 weeks pregnant & I was open with her before I even got pregnant I wouldn't have my kids around him... EVER. I don't want someone like him there. I had a horrible childhood so I'm already protective. Now that I'm pregnant I really am trying not to stress but since I found out it has been causing physical pain. I talked to my sister how I feel... and even told her I want a relationship with her, just not him. I don't want to be around him at all. It's not rhe best thing for my child. But in this I'm losing my sister and best friend.

Am I wrong for this? I'm so torn and it's hurting me. 😢