it was violently anger-making and disorienting and I had to keep calm in order not to be dismissed out of hand and increasingly I feel that all calm does is provide cover for the other end of the dismissal spectrum, the one marked then it can't be that bad.

This is exactly it, and I hate it so much. If you show your anger then you're hysterical; if you don't show your anger than everything's fine. The zone in which you are appropriately upset and therefore eligible to be listened to is about as thick as a sheet of paper.