I am sorry you are feeling so bad - that is a really rough situation to be in.
I commend you on your decision to stop drinking. One thing that has helped many people, myself included, is a good twelve step program, like alcoholics anonymous. The people there are wonderful at every meeting I have ever been to, they are a wonderful support group, and chances are they all have been through what you are going through. There is a lot of help you can get there, even if you go and just listen to other people's stories.
There is no quick fix to get your girlfriend back. But I bet you could get alot of good out of working on yourself and taking care of yourself. Even if you don't have a drinking problem, it is very hard to just stop drinking permanently.