Broke up with my boyfriend yesterday, he is cutting today.?

My boyfriend and I have been together for 5 months. We met in a short term mental care facility, he has agoraphobia (fear of leaving the house, social interactions) and I have bipolar disorder. We both have been long time cutters but have so far supported each other and been able to quit. We've been through the best and worst of times, we've had amazing days just gazing at the stars or having some wine with a dinner he's cooked but we've also had intense altercations and arguments. He has cheated on me three times and every time he doesn't get his way, he takes it out on me. He admits he treat me badly for three months but claims he has stopped. He hasn't. He tells me to shut up, get a back bone and grow up. He brings up my rocky past that I'm trying every day to move on from. He refuses to even try to do anything or go anywhere meanwhile, I like to be outside and active. We're too different and I've overcome my depressive side, but he's happy in his black hole. So, I broke up with him yesterday. I completely snapped and let everything out and left. Now, he keeps texting me telling me he's cutting himself, will slit his throat and overdose on pills. I don't know what to do. I refuse to be manipulated into staying but I will always love him and do not want him to hurt himself or worse. How do I prevent him from hurting himself without being with him?