My 2cents for what it's worth mroczek...
I'm wondering why you wanted to pursue a relationship with a chick that behaved that way toward you when she had a boyfriend

? No offense but if she was being honest with all the 'sex talk' etc she would've dumped the bf a long time ago so she could hook up with you.
I've come across many chicks like her over the years, basically they just encourage male attention for their ego trips. It's never their intention to take it further, it's just ego stroking power play.
You sound like a decent guy. If you re-read your initial post in this thread a coupla times over it'll sink in...she's done you a favour
By the way, I could tell you lots of stories about the psycho men I've encountered out there too fellas, but hey, don't want to turn this into an Oprah segment