I think the key is in realising you can FEEL terrible but you don't have to email/call, you can let it pass. Your mood seems to be up and down depending on the status of your therapy. Have you done much work on DBT and feelings? You don't have to panic and do anything.

To be honest your thread about T not leaving etc doesn't seem realistic. She may not PLAN to but it still may happen as things change. T saying therapy has a beginning/middle/end is more realistic and I'm glad you will be able to work with things together.

She isn't rejecting you. She isn't saying goodbye today. This feelng will move on.