I think it was abandonment.
First of all you have no responsibility to protect anyone's privacy. Your T does. You don't. If I see a coworker at my It's office I can tell any and everyone I want ( it might make me a jerk but it has nothing to do with legal confidentiality). Your T can not confirm that she sees this person, even if you already KNOW it. That's HER problem.

Second lots of clients in trauma work consider leaving T on a regular basis. I have told my T several times that "I'm never coming back!!" Etc. It's part of dealing with all the huge emotions. The therapist is supposed to be the rock that withstands those emotions and keeps this steady. My T will always say "well I'll leave the appointments open in case you change your mind" which I.always do.
So the fact that you considered leaving is irrelevant.

I think from following your posts she was maybe not a healthy match for you and you might be better off with a new T.
But I.think you have every right to feel angry and abandoned.