Another run like hell vote here. And there are a billion reasons why you should. Your love will not save him, it will only make your life hell, and enable him.
The ONLY thing I'd consider (and this may be bad advice as I'm not an alanon guy, I'm a sober alcoholic) is confronting him now with an ultimatium. Either he admits to a problem and gets help immediately, or it's over. Then, if it were me, I'd feel I did what I could. If he resents it, if it explodes in your face, etc. then fine. Gives you an even easier out.
Walking away from someone unhealthy can be really really hard, but I've found that the times I was able to gather the strength to do it, I grew in leaps and bounds. It was like I got an awesome gift after what felt like a huge sacrifice. The things that used to attract me (basically anything that lied, cheated, or needed some kind of psychiatric help), began to turn me off. I lost my attraction to those people and wound up in an awesome loving relationship that I've been part of now for 16 years.
I've seen heroin take down a handful of families. It is way more powerful than many believe. If you value your life and your future, I and countless others will say get out now. Nobody can save him. Only he can save himself, and he's not reaching out. Your leaving him might be the best way for his problem to start registering.