My Life History is Apparently NSFW

So I've refrained from writing about my new job here so far.

Several reasons I guess, when you've had as tough a time keeping one as I've had, you don't want to jinx it. But the first three months have gone fairly well, and I enjoy myself more often than not.

But something happened yesterday I need to vent about, even though its only tangentially related to work...

My boss and I have mutual acquaintances. We're both part of a large social network here in the city based around intramural sports, and as a result we knew many of the same people, even before I met for my first interview. I didn't realize we had those connections until after the interview though, when I was trying to figure out why his name sounded so familiar.

Apparently when he was informed of our mutual connections (I thought it was fair to warn him at interview 2 so he'd have all the background), he gave serious thought to passing on me because of the potential social dangers. Fortunately, my resume/interviews/dazzling smile must have won him over, because here I am.

Apparently some time in the last 3 months, he was at a sports-related social event with our mutual friends, one of whom is a past girlfriend of mine. For reasons that I cannot begin to fathom, she chose to tell him about our romantic history, including the detail that I was her first.

Yes, she told my boss I took her V card...

He informed me of this last night when we were working late on a project, and to distract ourselves we were discussing how she tends to overshare information. I knew she did that, but I figured she had enough self-control to think, maybe PRSlave's boss doesn't need to know about his sex life... apparently I was wrong.

Needless to say I've been stunned all day. Trying to decide the right response. Do I confront her and tell her how unacceptable that is? Do I let it go, knowing that she's an oversharer and that she has a particular issue staying quiet about me (she thinks I'm still the one, even though I've told her I'm not)?