Trapped

Hey guys so I've been going through a lot with my current bf. I feel like all we do is fight. He keeps trying to "work things out" but it's been 6 months and nothing had changed. He is honestly starting to scare me and idk what to do. Here is a list of some of the stuff he has done when we argue 
1. Drank bleach 
2. Say stuff like he wishes he was dead.
3. (Today) took a huge cooking knife and tried to cut his wrist (my sister had to calmly take the knife out of his hand)
Ik I'm not the easiest person to deal with so but this is just too much for me I'd rather focus on school. Can I please get advice on how to break up with him in a manner where he doesn't try to hurt himself.