[Kate*]

The tough part is that he has freewill over this, so you can only do so much for him. His not stopping isn't about the fact that you aren't trying hard enough, he's just not ready yet, as you already know, quitting can take years and sometimes it doesn't matter how much you do for someone, it's up to them to stop. Your anger is understandable, but he's doing it for some reason, even if you don't know what that is. If he's threatening suicide you need to tell someone so that he can get help.