Start by calling off the engagement and suggest he get some help for his addiction(s). Consider checking into a shelter for abused women. They will help keep you safe and can help you get started in a treatment program. Guilt is only what he imposes on you. There is no reason to feel guilt. He could choose to change his ways and maybe some day prove he is worthy of your love but more than likely that's not going to happen. There is nothing you can do or say to control his behavior or make him change. Only he can do that. You escaped the abuse of your mother and you can escape this too. I honestly wouldn't be too concerned about what he does to himself, I would be more concerned about him doing harm to you.