Help! Advice???

Okay, so.
I'm really stuck with what to do about my friends.
You see, I hang around with this group of girls, that I suppose you'd call popular. They're all really pretty and smart and nice to people they don't know tht well.
Everyone looking into the group sees a load of pretty, funny and nice girls, who ae best friends and generally loved by everyone.
Even though I hang around with them, I don't think I'm that pretty or smart or funny or anything, and I'm really quite uncomfortable around all of them.

The thing is, when you're in the group, it's a very different thing.
All the girls are sceretly jealous of the others in the group. They bitch and spread rumours and think that they're the best, but then, they act like they're all best friends.
It's all about appearances to them. Even when two people in the group are fighting, they still have to hang out with each other, because the rest of the group are scared of what people will say if they let one of their friends leave the group.
It's basically like that old saying "Keep your friends close, and you're enemies closer."
So, I really don't fit in with the group, mainly because I don't think you should spread rumours and secretly hate your friends. Most of the group are doing an extra year in school, so it's pretty clear that I won't be hanging around with them next year.

But my problem is, that I do really love one of my friends in the group. Next year, I'm in class with my friend who is in the group who I love.
She's sweet and funny, but still really down to earth and nice. She doesn't really get involved with tthe bitching, but she's best friends with the leader of the group, who does most of the bitching. The rest of the girls are either staying in the year below or moving to another school, and because she really likes them, this girl will probably still see a lot of them, which I have no problem with, as I won't see them.

I have one really good friend, who was kinda pushed out of the group because she didn't like the whole vibe and the others started to hate her.
We both remained best friends though, and now we're both going to be in the same class too. But I'm afraid that the girl from the group is still going to stay friends with the girls in the year below, so she won't talk to my best friend.

I know she doesn't really like her, but that's mainly because she's going along with the group. My best friend would probably still hang around with her, because they used to be great friends too.
But no, I'm terrified that I'm going to have to pick between the two of them, because I really can't choose.
I don;t want to lose either one.
So, I need some help!
What do you think I should do?
How can I stay friends with both of them without choosing one or the other?