Most Helpful Guy
Just end it, even more so now than before. He is holding you hostage emotionally. Nicely end it, if he threatens again either take him to the hospital for psychological help or inform someone close to him of the situation so they can get him help.
You are doing the right thing. He has to learn how to live his life for himself. Do not be emotionally blackmailed into staying with someone.
Help him get help, then walk away. His issues need professional help.