C.P.
I see a lot of girls this age acting the same way. My daughter never did this, however. I'm not really sure why. I have always been a very open parent and told me kids exactly how things were going to happen. Just tell her in a firm voice that you don't like her attitude and you will not deal with it. She is using the "nobody likes me" as manipulation. Explain to her that a lot of people like her but the little fits are not helping the situation.