I think that it's not fair for your friends to try and divide you and your girlfriend. "Forget her, date this other girl" is a really rude thing to say. If you really love her, stay with her,

BUT

Friends come and go, but, traditionally, boyfriends and girlfriends come and go faster. It's just the way it is. I don't think that you should let your friends push you or her around (these aren't true friends, in my opinion) and you can't choose them over her, especially if you really love her. However, you can't really choose her over them, either. A real friend would allow you to be with who made you happy. Better yet, they would WANT you to be with who made you happy, regardless of how they felt about that person. On the same a hand, a caring girlfriend will let you hang out with whatever friends make you happy.

Don't let either side damage your relationship with the opposite side. Be true to your friends, true to your girlfriend, and true to yourself.

I think Elle's suggestion of sitting your friends down with your girlfriend and having a nice talk about everything is a good idea. She's right, it'll make things better, or make them worse for a moment and then they'll get better later.

Good luck. Message me and let me know how it turns out.