That is unbelievably awful and painful and my heart goes out to you. 5 years therapy ending so suddenly, not to mention in the midst of a session, is truly devastating

Maybe in time you'll feel a little better for knowing this wasn't because she didn't care, but I know it won't help now.
The grief associated with an ending like this is too awful for words and I think you'd benefit from support with processing the pain and everything else it has left you feeling. I imagine it would be hard because your T was one of a kind and I understand that as I'd never find anyone like my T. Maybe if you go into therapy again not expecting to find anyone like her, just a safe and caring space to process the loss of the relationship, it might feel manageable?
I'm so sorry I don't even have the words. I know how deeply this would affect me. You're really brave for taking care of yourself in the best way you can right now. Please consider support if it all becomes too much.