Could i start anything with my friends boyfriend?

[stephx007]

so me and my guy best friend ended up pulling at a party, and i was really taken aback at how much i liked him. i thought something would develop until i found out my friend really liked him, so i backed off to let things cool down a bit cos i didnt want to hurt her. a few days later i find out they are going out. i was really hurt cos i thought he really liked me. now things are really odd at school, he's really flirty with me still and yet doesn't seem to be slowing down with his gf. what do i do????
to make it more clear for people, i shall rephrase it...
a couple of weeks ago i pulled my best friend (a guy), and thought something would come out of it. however, a friend of mine liked him so i didnt start anything with him in case she got even angrier than before. a couple of days later they start going out, and im really really hurt cos i thought he liked me. he still flirts with me loads though and i dont know what to do.
he is my best friend, and i value his friendship much more than i value hers, so i cant cut him out of my life totally. help!

[swin]

stay with ya friend, cus i think he's not that serious about either of ya, he sounds like abit of a playa

[brit J]

wow, um just stick to your friend and make him understand that hes wrong for doing that TO YOUR FRIEND.