<human>: Can you summarize the given text in a few sentences?

I'm friends with this girl, and often times when we go out she ends up hitting on me, and we'll have flirty banter back and forth, but I've always felt a little awkward because I know she has a boyfriend.

Last year, she cheated on her boyfriend. She told the boyfriend, and they moved past it, but she said she never really regretted it. They're stuck in the type of relationship where one isn't really committed and is waiting for the other person to end it, and the other one is so committed that he'll never leave her.

Now she's becoming more and more flirty with me, to the point where she's told me she wants to take things further with me, which I would be happy to do were she single, but she's still with him. We're going out clubbing with a few other friends in about a week, after which she's spending the night at my place. 

What should I do? On one hand, I know that she's into me, and I'm into her, and would go for it in a heartbeat if she wasn't with someone, but on the other hand, she's got a boyfriend.
<bot>: Friend that I would date in a second has a boyfriend. She's cheated on the boyfriend in the past (she told him). She wants to sleep with me. What do?