I think there is a difference between feeling anger and acting anger out in a manner that frightens others. Could you perhaps tell the therapist when you first start feeling angry before it becomes out of control for you and perhaps they can help you with changing behaviors or thinking patterns when you feel angry and lead to being able to discuss it without the anger taking control of you so as to leave you unable to get any relief. I have gone into the therapist before and started by saying I am angry - for me, doing that immediately can help release some of the feeling of force of it and help keep me from adding to the already angry feelings without adding more frustration to it.