Ignore her and go out and find another ; trust me don't wait 5 years for her to have a horrible breakup and then only get back together with the ex after a few days of dating you.
I think shes trying to get you jelous shes just a bit bad at it but its obvious bro all the flirting and saying she has a bf its CLEARLY trying to get you jealous and after her ;p she prob read some teeen magazine that told her to do this but trust me she prob doesnt ha ve a bf
id suggest 1 truthfully, aint even worth the possibility of the boyfriend knocking your shit out later on. or getting the chick preggers when she pokes holes in the condoms.
Get a video camera, have sex with her, record it, send it to her boyfriend, never talk to her again.
But anyway lol, i've had a similar situation, I ended up staying til she broke up with her boyfriend, never got the balls to make a move, got friend-zoned.... MAKE IT WORK MAN!