Good suggestions above!
Its normal - grieving a loss of a relationship, no matter how dysfunctional - is still a process. I think its because we grieve the loss of what could have been...the fantasy of it all. When I think about the reality of it, I am grateful its over!
I like soexhausted's idea of making a conscious point to address the thoughts and than banish them with a positive spin! I've heard folks doing similar things to stop the brain loop; being conscious of our thoughts all the time helps to control them.
I also try to stay busy, even if its boring tedious stuff. I get out and do things even though I really want to stay home and watch tv!
And I have thought a lot about my situation in ways to stop the obviously unhealthy patterns of choosing men who aren't healthy. When the time is right to date again, I will make sure to date "outside my comfort zone" because I think my comfort zone is what gets me in trouble!