I'm so sorry this happened to you. To me, it's a warning sign that your T brushed you off so many times. She should have listened to your concerns and not taken it personally that you didn't like the yoga instructor who appears to be her friend.
Have you talked about it in session, after telling her you were sexually assaulted and after she said this time, she will listen?
My advice would be to see how she reacts in the next session. If she really does listen and believe your words and your experience, and not defend the yoga instructor or brush it off, I think I would chalk it up to, your T made a mistake because she was involved personally, but she has learned from it. If she does in fact defend the yoga instructor, or not take you seriously still, it's definitely time to see a new T.