I think there's a big difference in disclosures between "this is happening now" vs. "this is what I've been through." I'd be uncomfortable with the first and have heard a number of things from my current and past therapists (different levels of disclosure) about their pasts.

I've found that disclosures about the past are helpful to me in my therapy. They never include excessive detail and there are ways that I learn from them, it helps me normalize my own experiences and it can reveal ways I'm thinking or feeling by having someone relate to my experience.

But like everything else, if your T's disclosures are not helpful to you, tell her. Talk about it or just tell her not to do it anymore.