If you were to go forward with this, what would you hope to gain? Whatever it is, think about it and ask yourself, "Is this going to give me some sense of closure or make me feel better in anyway? And for how long?"

Also, you would ultimately have to consult an attorney, but I would keep in mind that if a lawsuit were to happen, there's a good chance records would be subpoenaed and/or they would question the therapist.