First, the fact that you are a minor yourself could muddy things.

But if you were a legal adult, I'd say ask a laywer first, he could tell you what could give your therapist license to violate doctor-patient confidentiality. You want to make sure that if your therapist DOES violate it, he is breaking the law and you can go after his license and sue him into oblivion. It MAY be that in some states, you can't say anything about GL at all w/o taking a risk.