He hit me

on the second, he hit me and kicked me in the ribs. we've been together for almost two years now and he's not like that. He has split personality disorder and I told him I'd leave him. it was like a switch flicked in his head and I'd never seen that kind of look in his eyes. He got a knife and tried to split his wrists while repeating "I'm not a good person, you need to leave before I hurt you again." I stopped him and stayed. We cried together and held our son between us. I don't want anyone to tell me to leave him, but I'm scared of him now. I'm terrified that he will do it again. off it happens again, I will leave. I just needed to get that off my chest.

what can I do to help him feel like a better person again? I love him so much but the bruises are painful and my heart is broken.