The Alcohol Is Destroying Us...

we have been together for nearly 4 years. We met on the job together, I was a waitress, he was a part time cook. He is also a professional dancer/teacher, so of course one of the first (and incidentally, only) dates we ever went on was to a local shag bar.  I fell in love with him, completely, by the end of the first dance. we were both recently divorced, im in my 30's, thought i'd been in love before... never like this. I had, and still have, a physical reaction to him.
We both enjoyed going out, dancing, and drinking... but as time went by the amount of alcohol he was consuming just kept increasing... we no longer spent time together, unless I went to the bar with him, which would make it REALLY hard to get up and go to work the next morning... eventually he just stopped coming home completely.  His drinking continues to escalate, and now he is smoking pot (not a big deal to me), snorting cocaine(bad) and occasionally, Crack(REALLY BAD!)  I broke up with him yesterday. we had a long chat this morning (literally, on facebook). He admits that he drinks too much, and swears that he can control it, although he has lost jobs, missed court dates, and is now facing jail time...  I feel like I have let him down.  I love him so much, shouldnt I stick by him? Help him? How can I help a man who wont admit he needs it.  How can I help anyone in the condition Im in? The anger, sadness, fear and depression are killing me... I sat here and cried while I read everyone else's stories, because they all sound so familiar... and I recognize the pain...
I know that I am going to worry about him constantly. I know that it is going to take a very long time to get over him. I know there is no magic fix, although I will always wish for one.
I know his heart and soul. He has so much talent, so much to give the world...