This isn't a therapy issue. This is a services rendered issue. You were well within your rights to say "our time has not come to an end as you used part of it for your personal matters. I expect your bill to reflect that."

You are still within your rights to email your therapist and inform her that you are not pleased with the service you have received for the reasons above.

However, walking out, slamming doors, being snarky with your T, what is the point of any of that?

Also, bickering via email between sessions sound unprofessional.

Honestly, this sounds like boundaries are being crossed and the therapeutic relationship has given way to a dysfunctional friendship.