Trying To Help My Bf

Don't know where to start. I have always known that my boyfriend did hash, but recently he told me he's also done cocaine in the past. Started in '88, he's 32 now. I asked him to stop and naively thought that was all it took! I've never done any drugs myself - even alcohol and so I'm having trouble understanding why he does this. He hadn't done any cocaine for about 2 months, but two days ago he got really drunk with friends and ended up doing 4 lines. He told me next morning and he seemed to be really remoresful, guilty, even disgusted with himself. I'm so scared I'm gonna get a phonecall one night from a friend saying he's in intensive care etc. He's already been hospitilised twice in the past, once from alcohol once from drugs. What can i do to get through to him? How can I help him? Should I protect myself? We had a weekend away earlier this year and he was drug free for 2 days - best weekend of my life. He was interested, attentive, full of energy. Thats the man I love, the man I want. How can I get him full time and not just on holidays?

Any help appreciated.
I am sorta in a similar boat. My boyfriend is an alcoholic and two months ago he quit drinking. Since then he relapsed once - he was in total remorse and was very guilty the next day - He has left his previous job for a month now, and everyday he has been helping out some friends, all except today. Then I phoned him this afternoon, and lo and behold, he was drunk again. I have made a decision from today that I don't want to go out with him anymore. Me being a recovering addict myself - his drinking was not helping me at all. It was the hardest decision I have ever had to make because last time we broke up it only lasted 3 days and I am scared that I won't be able to stick to it.
It is so hard to be with someone who WILL lie to you no matter how wonderful a person he seems to be. My boyfriend IS a wonderful person, but his drinking has taken that person and hidden him away. My boyfriend is also amazing, but when he is not drinking and I don't deserve to only have a part-time man. And I have chosen not to be dragged into that again. I don't know if that might give you any strength or courage for what you choose to do, or even if you are going to stay with him - whatever you choose, make sure it is for the best of YOU.
Let me know how things go
xxx
JUST DUMP HIM, HE'S ON A ONE WAY TRAIN TO NOWHERE.