Sounds like an awful experience. It’s personal in that it happened to you, but not personal in that it sounds like this is almost entirely about the therapist’s incompetence. When you are doing your best to be earnest in couples therapy and trying not to be defensive etc you are just a sitting duck for being hurt by an incompetent or unethical therapist. It’s especially horrendous because they can take someone’s side against you.

Think about it: if you’re in solo therapy and you encounter a therapist who isn’t that empathic, you can leave. Also it would be rare to encounter a therapist in individual therapy who says something like, “I can see your mom’s point, you were a bad child!”

In couples therapy that happens All. The. Time.
And if you want to leave couples therapy as your relationship is crumbling it’s as though you’re not putting in a good faith effort, especially if your partner doesn’t see it the same way.

Anyway. I think wtf happened is that the therapist sucked and made you feel like your point of view wasn’t valid. I don’t find it so surprising. Bad therapists are a dime a dozen.