Speaking from experience (my ex therapist terminated me after two years and a half with a letter), I agree with Runcible Spoon: time and distance. The first two months after termination were rough not gonna lie. After four months it was no longer painful. Now after a 13 months I can say that I rarely think of her. Once in a while she pops into my mind and it feels like it happened in another lifetime. I would also suggest deleting/throwing away any memories you have of your ex therapist such as emails, recording of sessions, letters, pictures, etc. I know it can feel impossible to get rid of something that seems precious but those things are reminders and they feed the obsession (imo). Better to make a clean break in my experience. Good luck