I don’t know how to break up with him

I NEED to break up with my boyfriend. I have been iffy about it for about a month, but now I know for sure I need to. He has sexually assaulted me multiple times and lately just being around him stresses me out so much. But I don’t know how or when to break up with him, he’s manipulative. Throughout our entire relationship he has always said that he’ll kill himself if we break up, and even though I know he’s dramatic and exaggerates a lot, I am worried that he actually will do something, because he has tried before in the past. He’s also going through a rough time right now, so even though i know I need everything to be over I’m worried that it will make things so much worse for him and increase the risk of him hurting himself. I also feel bad because he has been trying to be a better boyfriend (since i very delicately mentioned the assault to him, and he has noticed that things are not the same between us as they used to be) and he loves and cares about me a lot. I just don’t know what to do!!