MST survivor here. See your V.A. therapist. You should have a therapist at the V.A. Please tell that person what happened. It is my hope that you have a good relationship with your therapist. What your "group leader" did was wrong. That is my opinion. No one has ever "heard" everything... to be "blown off" during the course of treatment especially when you express that symptoms are presenting ("Flashbacks") is just plain ol' wrong. Again, in my opinion, that group leader was supposed to TAKE YOU to your therapist... especially when you have serious symptoms presenting. See your therapist. It only gets better with adequate help.
Yours in survival,