I know exactly how you feel, I know someone like that, I'm not even friends with her but she's so nosy and if I ever try to tell her to get lost, she gets really annoyed with me and makes out like she wasn't in the wrong or anything. She seriously bugged me one day when she started talking to me on msn, I posted what she said to another friend who told me she was waaaay out of line.
I think the best thing for you to do is either talk to your friends or just drop them. I know it sounds difficult etc but thats the only way. I was friends with some people who I later discovered disliked me and talked about me 24/7 behind my back and even though distancing myself felt like the hardest thing to do because my other friends had their own groups, it was the best thing. I soon found new friends who properly cared about me.
It sounds like your friends are talking about you in that way because they think that just because they have boyfriends they are superior to you in some way, and people who talk about you like that are not worth knowing. It may seem the hardest thing in the world to find new friends but its way better to be on your own for a while trying to find new ones who'll be good friends than staying with ones that are making you unhappy, sticking with them won't help you in the long run.