am sure they were your friends in good times only. Goodness, and the backstabbing, professional jealousy... no way to stay friends with this kind of pipol, they may be fun to be with but the friendship ends there...
Well, if you are strong enuf the next time they say something about the other you can tell them frankly that you are not comfortable with it then joke about "hopin ur not talking about me that way when am not with u gurls"! Later on you can tell the person concern, or if really really you can't do all this, then my dear the best way is to just stay away from your friends and make new one with the mature minds coz it is not a healthy relationship you have with your group my dear , sorry to say.