Perhaps I’m a little dense but I’m failing to see what’s mortifying or apology-worthy here.

You meant you weren’t going to be able to accomplish much that day because you were emotionally drained from therapy, right?

It sounds like she was sort of suggesting that since you’d just had a big session, that you not tax yourself further if possible.

So you were basically agreeing with her.

If your personal trainer had just worked you to your limit would you play it cool and be like, “me? Tired? No, no, I’m actually running a marathon right after I leave…”

You weren’t rude at all. But even if you’d been a bit sharper, it’s okay, you don’t have to take care of your therapist. That’s why you pay her.