I'm so sorry you had to experience that. I know exactly what you're talking about. The only person I share those things with is my T and to a lesser extent my psychiatrist who I'm starting to trust a little more now. It took me months to gain trust in my T. GPs are not trained in mental health and probably know even less about PTSD. His threatening you is going to do more harm than good. He sounds extremely insensitive and shouldn't be expecting you to spill your guts on the first visit.

Trust issues are a big thing with us but few people realize this, even medical people. You don't have to tell anyone anything if it makes you uncomfortable, that is your right as a patient and a human being.

If the GP wants info about you ask him to talk to your T or ask your T to call him to straighten things out and explain to him some things about PTSD.