Yes. Oh my yes. I can relate so much to this.

Here are my thoughts. I am not a T and don't have a lot of experience with going to therapy. But I read a lot, so I know a little anyway. I think that your T was completely sincere when she said she appreciated your letter. You told us about it - you were being honest and open, and that is what Ts (supposedly) appreciate most of all. She's a T, she knows that everything her clients say about her isn't necessarily about her. That she called you back shows that she is concerned for your well-being. My untutored opinion is that 1) this T is on your side, and 2) even though you are dependent on her right now it doesn't necessarily mean that you always will be dependent on her. So I would advise you to go. Especially since you know you won't see T for a couple of weeks after this session... my guess is that if you don't go you might fret about this more while she is gone, than if you do go.