HELP MY BFS MOTHER IS A MONSTER

I'm having problems with my bfs mother. She's always had an underlining displeasure towards me and knows that I will be the one help him move on and move out. She has recently went through a crazy fit including screaming in my face, pushing me and kicking me out of the house 2 times in 24 hours. I just spent my first night back in the house 3 nights ago. Everybody involved has reasons to believe that she was on meth. Her own sister, who's a drug addict/dealer, admitted to doing lines with her days before she freaked out and said she was coming down. She's even admitted that her sister has been doing meth for years. She's acting like everything is okay now because she claims that she blacked out and nothing is her fault. I've been trying to get my bf to leave with me, but he said that if he leaves and she over doses, he'll blame himself. He kept telling me to go live with my mom in Louisiana and I wanted to stay and try to make it work. Things are not the same anymore. She's wanting to force us to be happy when my bf has suffered years of emotional because of her. He is not happy and we were working so well on that before this shit happened. She's trying to control what he does and the same with me. I'm getting mixed signals from him. He told in the beginning to leave but when we have our tiny happy moments he says that he's happy I stayed. When he drinks, he becomes more harsh with his words because of his depression. I think everything is okay until she rips him away from me and make everything about her. I work on getting him to sleep and eat, and then she ruins it by making his already bad anxiety worst. I would have left by now, but I love that man with all of my heart and soul. We have both agreed that we're each other's soulmates. He's the only thing holding me back, but there's only a shell left of him and it's her fault. I wouldn't mind trying to make it work, but she refuses to admit that she's been on meth and I really don't think I want to live with someone who fly off the handle whenever she wants to. She's always been this way and she won't change. My mother was a drug addict and I was taken from her when I was 10. I know that drugs do things to you, but she decides to stay in denial about her problems. My mom is supportive of my relationship with my bf and she wants me to be happy. I feel like I couldn't be happy like we were before. She wanted me to come live with her, but she knows how I feel about my bf. I know this whole thing has been all over the place, but IDK what to do anymore and my anxiety is through the freaking roof. What should I do????