There is no quick fix. You first have to realize that the thoughts themselves are not the problem. It's how you are reacting to them that perpetuates the problem. It's easier said than done, but you need to stop reacting. Thoughts are just thoughts, not calls to action, not indictments, not predictions. It's just information. You choose what to do with that information. Not every thought our minds present to us have any basis in reality.

Have you read any books on OCD? I would recommend "Imp Of The Mind". Seeking out a professional that specializes in CBT would also be very helpful.