Why is he being so morbid and what can I do about it?

My boyfriend (sort of – we’re on a “break”) has recently started acting really weird. He gets mad at me a lot, and then will go days without talking to me, saying he needs to be alone. Today he told me he doesn’t want to live. I asked him if he wants to die and he said “you’re taking it too far”. I don’t really know what to do because he keeps pushing me away. Also, I have a history of major depression and suicidal tendencies, so hearing him talk about death and stuff makes me very uneasy as it’s still fairly new for me. What is going on with him and what should I do? When I ask him what’s wrong he either says “nothing” or changes the subject.