First, I am sorry. Last year I felt the exact same way. I heard a lot of threats, I spend a lot of money trying to figure out if my stbxah could actually do what he threatened. After a while, I stopped believing that he actually had any power. It took me a long time to realize that I had parental rights too.... For me, the bark was always worse than the bite. My stbxah is still very very very angry at me, but now the threats don't bother me quite as much.
As for staying or going, I left our marital residence with our 2 yr old at the time, I was to attached to him and his recovery that I had a hard time detaching so living with him did not work for me. I was having such a hard time with work and taking care of our daughter that I had to get out to save myself and my sanity. Now I am more detached and could probably live with him in "recovery" but I now don't want to. Isn't that ironic???
I feel like I missed out on time with our daughter because I was so worried about what he was or wasn't doing. Do whatever allows you to be the most present with your child.