Whether or not he dies has nothing whatsoever to do with you. He is trying to guilt you into staying with him so of course, he threatens to kill himself of just go out and use and not care what happens to himself. It's all a load of BS. The man simply is not interested in getting and staying clean. Nothing you say or do is going to change that.
You can continue to ride on this roller coaster for another year or you can decide that you are done with it, regardless of what he says he's going to do. No one is forcing you to stay with him. You hold the key to your freedom.