If you can’t stop talking about it, you’re not over it. You can’t move on until you have let the past go, so do what you must to deal with it, and let it go. Sometimes that means talking to the person in question; sometimes it means coming to grips with the fact that you can’t right a wrong. Sometimes it is enough to sit in silence and feel your feelings, and then say goodbye to them. Whatever it is, do it and then be done with it.