Maybe the dreams about the good times with the ex are merely a manifestation of your desire for intimacy again? I know my widowed friend has those dreams mostly when she's in a mood to date (almost like an emotional wet dream). Consider that the dreams and thoughts about him might simply be you missing being in A relationship , not necessarily THAT relationship.
If you really think you just can't get over your selfish cheating alcoholic husband - consider reading the Alanon book The Courage to Change. Even though my ex was not an alcoholic, a friend gave me this book when my ex left and I found it helpful.
Now some people genuinely have no desire to be in a relationship after divorce and that's fine. But you might consider casually dipping your toes into the dating waters just to see how it feels. I will say every man I've dated since my divorce has been more appreciative of me as I am than my ex ever was and that's been wonderful.
