I was thinking it sounded a lot like individual therapy between the T when I read the first part of your post. It took me so long to find a T that I felt ok with, it seems near impossible that one T could work well with 2 people in the same session!

I think wtf happened there is pretty much as you said...the T was on your partner's 'side', for whatever reason. So the therapy couldn't be helpful, she wasn't mediating, it sounds like she was punishing you for not being who your SO wanted you to be.

Of course your feelings are valid, the things you tried to bring up in sessions were very important, it just really sucks that you didn't have a very good therapist to treat you both equally.

The end of any relationship can make you feel like you failed, but it doesn't sound like you did.

The fact you wrote this post shows how much you cared and tried to make it work. Honestly, it really does sound like the T was unprofessional, seeing as they got so mad and shouted about it.