Talking to Horrible In Laws

So a little over a year ago we had a huge falling out with my SO’s family. They’ve hated me and treated me really badly ever since they’ve known me. My SO was 19 when we met and his mom would cry every day that he was spending too much time with me (he also worked/lived with his mom at the time). We even had to hide our relationship because he was afraid of her. Eventually we were openly together, living together, and happy. I was even 7 weeks pregnant at the time and we were thrilled. His mom did not like this. The falling out happened when his grandma came to our house, started packing his things for him, and telling him he needs to leave because I’m “controlling him”. He wasn’t even home when this first happened but he got there in the middle of all of it, I had said something along the lines of “she’s crazy and she won’t leave” and she hit me right in the face. Obviously she was forced to leave after that (I should have called the police tbh) and my SO talked to his mom where she basically said “you do need to leave, your memaw said she tapped her face, not hit her and she’s just dramatic”. To make matters even worse, I had a miscarriage the day after this all happened. He decided to cut his mom, dad, and most of his moms side of the family off after that. I feel bad though, I know he was very close with his family before me and I feel like him cutting them off only affirms their beliefs that I want him all to myself. What should I do? He still says he wants nothing to do with his mom or dad but idk.. I just feel horrible. I have a bad relationship with my mom and dad too and I don’t want him to have to feel the same way. But I also don’t want to be treated like worthless garbage by his family anymore. What should I do?