Betrayed and confused?

If I were you, I'd ask the girl who was talking about you if she really said those things. Tell her you don't want to argue or be mad, you just wanna know why she said those things. If she denies it, then there's not much you can do. If she comes clean about it, tell her that you would rather her not say those things about you, because it hurts a lot. Also, tell her that not everyone is perfect, and that if one looks for flaws in a human, they are going to find them.