I don't know if I want to be with him anymore

He won't let me leave... I'm 3 months pregnant with my first, and he wants to marry me. But he messes with my emotions, calls me names, brings up the negative of both our pasts... but then on the other hand he can be really sweet, attentive, smart, and seems like he loves me. But then some days on the bad ones, he has became physical at least a small handful of times.. I feel so stupid I can't walk away from him so easily, and I've wanted to every time. Then the honeymoon stage kicks in and it's like he uses my love for him against me. He has some mental illnesses, that he says he'll start his medication again for. But I don't know if I can trust this and I don't know how to get away from him, especially now. I won't talk to anyone about it because I'm so ashamed, my mom had multiple abusive partners so my family will just rub it in my face. What do I do?? How do I numb myself enough to leave??