That sort of obsession is horrible. One thing I have used in the past to stop myself was to allow myself to run the entire scenerio through my head. If its done with enough detail, it can sometimes keep you from hurting yourself. Since you can't not think about it, just fantasize it.

I don't know if that is an accepted thing to do, I only know that it worked for me quite often. Have you ever been really angry with someone that you knew you would have to confront and fantasize about what you would say, how they would answer and the conclusion? Its a lot like that.

Sam2