What he did is awful. I dont know why he did it either. Perhaps he was not comfortable telling you his truth. You did say he has issues. Perhaps he is a jerk. I don't know. Ways to move forward: know it is ok to not have peace right now. Write him a letter and burn it or tear it up. Write him lots of letters and dont send them. Talk to a counselor or someone you trust about how you feel. Post here. Distract yourself. Do somethings you enjoy. Know it will take time to move on. Did this happen recently? Work on yourself and your own happiness. I'm sorry you are hurting. Hug.