Shea:

It is hard to be in a relationship if there is an extra person floating around
It is hard to be in a relationship if there is an extra person floating around, especially an old wife/lover. What is it that he does or says that makes you believe he isn't over his ex? Sometimes we let our thoughts and fears get the best of us. If you love this guy, you need to get to the bottom of this and at least give him a chance to tell you whether or not he still has feelings for his ex. Listen with an open heart. He may have feelings for her, but also know that they don't work together.