I was in that place yesterday. Can you tell your boss you're sick (Technically you are) and go home? Just climb into bed and rest.
When can you see your T again?
I'd also write down exactly what you are feeling NOW. It'll be hard to recount it properly tomorrow. Then make an effort to see your T and let her read your notes on your feelings. A T will help you work through this.

I know right now is painful. We need to learn which of these feelings are genuine, and which need to be discarded. Then we need to analyse the legitimate feelings and work out where they come from. This is a BIG part of therapy.

Sorry things are so tough!