What a horrible and distressing situation! I would struggle with this as well. I do think it would be good to bring this up with T if you can. As painful as that would probably be, the other options might well be worse in the long term. I think your T would want to know what's upsetting you and it's very unlikely you could continue therapy with her with such a big issue kept secret. It would have to come out eventually.

Obviously only you can know what's right for you, but I do believe that sometimes these truly awful and what seem like impossible situations can pave the way to something better. Knowing that T is human too is tough and I agree there are limits to what we can tolerate and certainly to what we want to know about T, but once these situations arise, they can be worked through and there's tremendous growth in meeting T's humanity with your own. It depends how deep you are able to work with this and indeed to what extent your T can help you manage it. There can be a way out but it takes hard work and commitment.

I do know a few things about my T although nothing like what you've described. She has had a hard time (she hasn't said this but it's clear). She has also made big mistakes that relate on some level to ones I've made. But in accepting her mistakes i've began to accept my own. That's where healing really begins. Some people couldn't work knowing anything about their T and that is fine. But I like meeting my T as a human being who is real rather than a blank slate who is godly and apart from the rest of the world. For me, growth comes with having a real relationship, within reason of course as she is still a therapist, in the therapy room.

As I said, only you can know what's right for you in this situation. But try not to make a snap decision based on what you feel you can't tolerate because once you really look at this and what might be contributing to your intolerance you could find your perspective changes and you feel better for it.