I think it takes time for those thoughts to go away - especially if they are attached to alot of anger and emotion. I know one thing that's helped me is journaling and talking about all the feelings that come up with a therapist. It just gives me space to vent and process that's really helpful. Just getting some validation from a third neutral party is good, but overall...just feeling all the stuff that comes up. It's amazing how disconnected we can become from our body and emotions and that's basically what the therapist had me do...feel every emotion physically and talking about how I felt. The intensity of the thoughts and emotions has really decreased after that so I don't feel it's robbing me from enjoying the present.
I also found it useful to limit my time on this site when I first was out because it's stirred up alot of negativity - everything was a little too fresh. Now it's fine. I wish you the best - obsessive thinking is the worst!