I'm sorry you feel so hurt and betrayed. It sounds like she was actually very caring, flexible and accommodating in that she immediately got you back on her schedule for 2x per week (just not on same day as before, right?). So you still get to see her twice a week? Or did I miss that?
If I have to give up my second weekly spot with my T (which I will be doing soon) it will probably be months before she can get me back in for that second weekly appointment should I ever request that...and there definitely will be no guarantee for same time and day. Honestly, I probably wouldn't ever get it back because she has a waiting list and I respect that she needs to keep all of her openings filled. She's in private practice so I'm assuming she can't afford for slots to sit open.
I'm not trying to diminish your feelings of sadness, just pointing out that your T sounds very caring and flexible by immediately fitting you back into her schedule despite your cancelling your second session for the foreseeable future. She had no way of knowing that your new schedule would only last for a week. In fact, if you guys had been discussing it so extensively for two months then she probably assumed the schedule change was pretty well set in stone.
Hang in there! Your T sounds very caring and committed to you