I really feel stuck. Any advice?

[Carissa]

My boyfriend and I have been together for the past year. He's bipolar and has other problems that he refuses to take his medication for. Here recently, there's been too many "downs" in our relationship. We fight constantly. Especially over what I wear, I can't talk to guys, I can't hang out with my girl friends, he doesn't like for me to go out in public if he's not there, and if I get on social media sites he throws a fit. He cheated on me in the very beginning of our relationship and now he's even told me he's "scared I'm going to get him back." I'm tired of fighting, arguing, and being treated wrong. I want to be independent and leave but I feel stuck. I've tried to leave once before and he told me he was going to commit suicide. It feels like he wants to be in complete control over me. There's more that he's told me he'll do if I leave him, but I don't feel comfortable posting it to the Internet. If anybody can give me advice on how to safely leave this relationship, please answer.