I'm worried my boyfriend will hurt himself if i break up with him?

Talk to him about it, just tell him you don't feel very comfortable or happy, and if he starts to go off, slow him down and tell him, if he ever needs anyone to talk to you can always make yourself free to him. And that you will always be his friend to talk to when he needs. Check up on him as well and if does show signs of depression. I think it is best you call a doctor, but try to befriend him. Your out come might be better than you think. But don't just try to forget about him. But don't keep dating him because you feel bad. Cause then you can easily depress yourself.