Dudes! Question about woman and partners!?

I'm looking for someone, a girl, and i'm kind of falling for one. And right off the bat, she tells me how many guys she's been with. Which is 20. She says she's turned her life around and that was while she was in college five years ago. I mean, i've messed around with her a few times and she is nowhere near giving it up. I know your supposed to like a girl for what she is, but the partners thing is irking me immensley. What do you think is over the top? Thanks