@Confidentally-lost23,
Is this woman getting counseling? Because if she isn't, then she should.
Abusive relationships mess with people's heads, big time. If she is going back to her ex for last licks sex (sorry for the bad pun there), then she's got issues that your kindness and affection can't cure. She needs a doctor's care to figure out just what a bad move this really was.
She asked you if she had done anything to piss you off? I mean, sleeping with someone else would be high on nearly anyone's radar of things to be pissed off about. So she's also incredibly non-self-aware as well.
Be her friend (probably a better idea right now, anyway), and encourage her to seek medical intervention if she's not doing so already. That's what good friends do.
And in the meantime, if you see someone else you want to date, male or female, don't feel you have to hang around, waiting. You don't have to.