It's not easy to "unlove" someone. Actually you don't have to unlove him. You mainly need to just stay detached from him. In time your warm emotions will cool down. Keeping away from him will help that to happen.

He's going to have worsening problems. As his life spins further out of control, you'll be increasingly glad that you're not tied to such a loser. I'm afraid that's what he is. It may be that this is all he is capable of right now. No need to judge him. You only have to judge whether his way of living is acceptable to you. If it were, you'd be headed in a bad direction yourself.