It is possible that this constituted malpractice, if  in the giving of this opinion, the therapist violated the current, commonly accepted standards for how such counseling should be done, what advice should be given to patients or what diagnosis made, etc. It would be worthwhile for you to consult with a malpractice attorney--many provide a free initial consultation, specifically to evaluate cases and see whether it's worth proceeding--to understand whether, in light of all the specific facts of your situation, whether you have a malpractice case, how strong it is, what it might be worth, and also what it would cost to puruse it.