Stop looking into the past to feel bad about yourself. You have to take care of yourself fist before you can help others. I do not think it was such a bad thing when you slept with her. At that time, you both had a need. Maybe a healing took place for both of you at that time as a result of this. Each event in life has its reason and time and place. Your suffering will end when you feel better about yourself. I think you can be a healer, for you and others.