Well... I can't see how its a bad thing to enjoy having sex. It sounds fine so long as you are doing it for the right reasons and not as a coping technique for whatever other issues you have.

If your sex life is bothering you so much, I suggest you hold off on it until you feel more comfortable with it. You don't need sex to have a good time or to enjoy a relationship with anyone, including your ex. The choice is yours, though. Just be smart about it and make sure its really what you want. :]