Betterdayz, I feel for you and the world of hurt your situation is causing you. I can only imagine the sadness, betrayal and disappointment you must feel after a long-term relationship did not at all turn out the way you imagined. Although under very different circumstances I found out after 8 years of my relationship that a "parallel" relationship existed. The feeling of lost confidence and betrayal still, after 3 years, sometimes washes over me with such pain that I can not breathe. I give you a lot of credit for trying to maintain a clear head through all of this. I agree that you should try to not get drawn into a game of push and pull. Regardless whether mental illness is involved in your triangle and regardless of what you think he feels for you or her both he and she need to be accountable for their choices and the results of their choices. Your ex bf made a choice and has to live with the consequences. You alone can make the choice how this defines the relationship with you. If you can live with being a second relationship "on the side" without that scenario producing constant suffering for you then you should make your terms clear. If an exclusive relationship is the only condition possible for you then you should equally make that clear and walk away from the triangle. I recommend no contact as anything you do will form an ecouragement to keep you around and entangled in this triangle. I know it is easier said than done. I had to do a lot of soul searching myself in said sitution three years ago and found out that exclusivety and trust that I am the only person in my partner's life are the only way I can be in a relationship. The hard consequence is to walk away if I can not have that. Not to punish anyone or because I do not love or understand the other enough. Just to keep myself whole. You deserve that too!