I think I'm stalking my ex
Why do you think you're stalking your ex?
I keep going back to his facebook page and I can't stand it how he has a new girlfriend now.
Oh, that doesn't sound healthy. You shouldn't be stalking your ex. In fact, you should keep them out of your life entirely.
No. I need to talk to him and make sure he's not doing better then me.
It isn't good for your mental health to keep tabs on your ex and put yourself in that sort of competition with them. When a relationship is over, it's best to move on. Have you considered talking to a therapist to help you process your feelings around the end of this relationship?