What do I do?

I’m currently 30 weeks pregnant and high risk. I give birth in 6 weeks via C-section. Most of my pregnancy, my fiancé(?) has been physically abusive, same with the last pregnancy. Every time I leave, he promises to do better. Well we were doing alright then we allowed a family member of his to move in. This family member is normally very sweet, but once he moved in he started getting rude with me. He sits on my couch all day playing video games and acts like he doesn’t have to respect me. He’s always being disrespectful and rude to me as well as my daughter (who is 1) Andy nephew (who is 2). Every time I bring this up to my SO, he changes it and says I’m rude. This family member has even went as far as beating on my door while my SO and I were speaking, and told us to shut the fuck up. Anyway, tonight was the night I decided I was done. My SO and I were arguing about it him again, because I just can’t take it. I finally got tired of it and told him to turn the game off and get off my couch. He didn’t hear me so I said it louder. Then they both spent the next hour or longer screaming and cussing me. And the family member even watched my SO hit me multiple times. He stood there with a smirk on his face. It ended with me having to leave my home (that I pay for), because they wouldn’t. When I left, the family member stood in my doorway with a smirk on his face and waving. My SO has been messaging me for hours and has yet to ask me about our daughter once. The only thing he says is that we have to figure out a good way for us all three to live together. I told him I didn’t want to be there, especially if the family member would be staying. He said that’s fine and he wouldn’t turn his back on him. So now here I am, going to give birth in 6 weeks, searching for a new home and trying to get things ready for my baby, while also dealing with them calling people telling them I abused them both. They both even went as far to say if I leave, they will both call the cops and say that I beat the shit out of both of them. I want to leave, for good this time. But I don’t want to lose my kids because they’re going to say that. What do I do?