This sounds very painful. I am sorry your T's pregnancy has brought you so much suffering. I believe, it's a huge mistake for any therapist to promise a client that they will always be there for them to help them through whatever they have to go through. No one can or should promise that because we never know what circumstances we will find ourselves in. This especially should not be promised to someone with the history of such severe abuse and abandonment like yours, and your T should've known better.

It may help you feel better if you tell her how you feel about her leave or write her a letter about it. You don't have to trust her to do that. This is just for you to let your pain out instead of stuffing it inside and cutting yourself. There are times when we need to be completely selfish to get through the darkness. Tell her how you feel for your own selfish reasons, not because you trust her. It may happen that you will be able to process this with her and your pain will subside and you will make the best of the time you have left with her. Or you may decide that you don't need to see her anymore and find another T. Just do something and do it for yourself. Don't abandon yourself even when the whole world abandons you. In dark times like this, you are the only one you have to take care of you. You don't deserve to be abandoned again so don't abandon yourself.