Is Brentwood in the US? If so, you do not have to sign a confidentiality consent form for anything other than the release of information. Your confidentiality rights are automatic. If you signed a consent form, you likely signed something giving your therapist permission to talk to your parents. It is easy to revoke a consent form. Just write down that you revoke any previous consents for release of information about you, sign it and give it to the therapist. Keep a copy for yourself.