Struggling to find words. I'm sorry you're going through this.

At least it was nice of your T to sit with you. Even so, I kind of hope she eventually gets to a place where she can give you more of a closure. Obviously, it's not realistic to hope she'll start practiscing again, but ... dunno, an exchange of letters at least, or ... I don't really know, what I do know is it's terribly untherapeutic to quit on someone like this, even though quitting seems like the ethical thing to do in principle.

I second (or third, or whatever) other posters' advice to consider seeing a therapist/counselor just to help you with grieving. Especially since this sort of grief is otherwise very difficult to share, because not many people can relate. Of course, many Ts can't either, so you may have to be some combination of careful and lucky to find adequate support. But this is hard, to cope with the loss, and also to reconcile the caring and reliable T that helped you so far with this sudden abandonment (however good her reasons might be).