Kate, I agree with others that it's not unusual to charge a fee for no-shows. The therapists I (or my family members) have worked with charge the full cost of the session if you cancel within 24 hours of the appointment. However, they do not do it in very pissy way, which is the sense I got from your description of your therapist. (My daughter's therapist charged us full fee when my daughter had to cancel with less than 24 hours notice; she was polite about it, but firm.) Especially after recently standing you up, it seems like your therapist could have been more generous and understanding, perhaps saying something like, "well, I missed your appointment a couple of weeks ago, so let's just call it even."

It doesn't sound like it was clinical at all. It sounds like she was pissed off because you missed your appointment and questioned that. Maybe she has a problem with people who challenge her authority. Whatever. Good riddance. If it were me, and the bill was just for the $50 cancellation fee, I wouldn't pay it. Or I would mail it back together with a $50 invoice for the appointment when she stood you up along with a short message: please accept this invoice in lieu of your charge.