This situation is crazy, if you know about obsession please help! Its long, but no boring bits!?

The guy that your ex is after/not after now is, in my opinion the bad guy here. Although she did leave you, it was because she had feelings for him and thought it was unfair. At least she didn't end up cheating on you with him. And if she really does cut all ties with him,(which is doubtful) you must ask yourself why you don't think it's a good idea for you two to be together. If you two really do love each other, then maybe you still have a good chance if it's a reason that can be worked out. But if it's a serious reason, then you shouldn't really consider it.