So she's single and had sex with a guy...that's a hectic past? Are you just concerned that she's a whore and that if you start dating her then she will cheat on you? Just play it by ear. If you're gonna do her, it should at least come naturally (no pun intended). She's obviously not just some random girl, right? C'mon man, its not everyday that you get an opportunity like this. Learn how to use the rubber, strap up, and git'r done! ;)