Some goofy friggin advice in this thread and some that is decent.
I am not, and never have been, the jealous type. My attitude has always been, if she can do better...go for it. That means I can do better as well.
Its all about your own self-confidence. Feel good about yourself, you are banging a real hot chick (according to you, a pic would verify). She seems to want/need the attention of others...so what. Don't make an issue out of it, she may be just trying to get a rise out out of you/push your buttons/ or test your self-confidence. I have no idea since I don't know the girl.
I know that women find people who are confident in themselves (not !@#$-type cocky, but confident) to be sexy. I also would not want to be best buddies with her guy friends from work/guys hitting on her in the bar etc. Hot girls don't get hit on randomly as much as you think, their looks intimidate most guys. Thats why many hot chicks end up with uglier guys, the ugly guy showed enough confidence to hit on them (either that or a fat wallet).
Man up & be confident. Ignore the bull and you will be better off.