From your story it doesn't sound like anything bad happened in the counseling sessions. They were doing exactly what they were supposed to do - convince you that what you were doing was wrong and teach you to stop. If someone is doing something that's wrong and they don't even think it's wrong, then breaking them down like that is the correct solution. Imagine someone who's convinced that skinning animals alive is harmless going through the same kind of treatment that you did - now it sounds completely reasonable, right? Your opinion might be that skinning animals is worse than being gay, but that's just your opinion, and both views are equally valid.

Trying to cure someone of what you believe is a mental disease isn't wrong, regardless of whether it really is a mental disease or not. Trying to free a loved one from a compulsion to do what you believe is a sin isn't wrong, regardless of whether it really is a sin or not. The only person who did anything objectively morally wrong was you - lying to your parents.