I had a boyfriend like this once. I tried to help him but in the end I couldn't handle it anymore. He always told me, he would kill himself if I ever left him. I told him many times that I'm not responsible for his life and that I cannot and don't want to be made responsible.
I told him I felt extorted, but he just didn't stop. It was so exhausting, in the end I had no power left to bear him and his problems any longer.
So I left him, explaining exactly what the problem was.
Needless to say, he did not kill himself.
I'm not really sure what to tell you, OP. Just be careful - when this relationship starts to hurt you, you need to get out. Don't let it consume you. Taking damage youself won't help you nor you boyfriend.