Nope. You don’t admit these kinds of things. Especially if you were an epic man whore. The next time your girlfriend inquires, tell her this:
“Honey, we live in a world that has walls, and those walls have to be guarded by men with guns. Who’s gonna do it? You? You, Ashely? I have a greater responsibility to protect you from my sex number than you can possibly fathom. You weep for my penis, and you curse the unknown women it slept with. You have that luxury. You have the luxury of not knowing what I know — that all the sex I had, while tragic, probably saved a girl’s life, once…maybe; and my sexual past, if you don’t want to think of it as being grotesque and incomprehensible, should not be talked about, ever.”
You should never assume anyone — man or woman — can handle the truth. Personally, I don’t understand the need to know. In fact, all anyone in a relationship needs to know is not a number, but that the other person is clean.