I know what you mean, sometimes I stay up until all hours of the night so that when I hit the pillow i'm just too exhausted to think, otherwise I will just worry myself into anxiety and depression. I think all you can do is try to limit your focus on the negatives. Personally I find drinking and cigarettes don't help very much, but I understand why you rely on them. I had a relationship where I though I would marry the girl, when we broke up it was a really bad break up, all I wanted was to have her back the way it was when I was head over heels for her. I would always remember this one night, the most romantic night of my life, and I just wanted to go back to how we were that day, even typing it now I still miss her, but I moved on and I found someone who makes me really happy. I don't think you can ever recapture the past and to try to do so can lead you down a very bad path. I'd suggest you read The Great Gatsby by F.Scott Fitzgerald. Gatsby wanted to recapture that past instead of moving on and it led him to his demise. I think you need to try and move on and let those memories remain in the past.