I’m so sorry this happened to you. The timing of her being on another vacation is devastating. This is a rupture you should never have had to deal with, period, and to have it dragged out like this? Oof.
I back you 100% that she lied to you at some point. Also, there’s a difference between opening a letter she knows she wasn’t supposed to and actually reading the whole thing. Like that part is so shocking to me. She said her first reaction was a “oh shit, wasn’t supposed to open that,” the part of me is screaming THEN WHY DID SHE KEEP READING! I’m honestly livid. As another PTSD sufferer, I’m so pissed that the sacred safe space you built with bloodied hands was so flippantly tainted like that.
Personally, I would see how the next session goes. When I went through a big rupture with my T, I wanted a potential “last session” just so they could see how pissed I was, how so not ok what they said was. Surprisingly, my T was able to repair the trust and navigate the rupture with me.
To be clear, you should do what makes you feel most safe. That may look like terminating with her over email or text. It may look like you walking out of session 10 minutes in because she can’t repair. It may look like this rupture becoming the new cornerstone of a deeper trust with your T if you choose to continue with them. Whatever it may be, I feel for you.