Don't listen to them! I see how you sit in class with your hair hiding your face and your eyes looking sad. You've been believing everything they say, haven't you? You think just because they're popular and "cool," that what they say must be right. After all, they must know what they're talking about since they're "all that," right? You couldn't be more wrong.
Research shows that mean girls pick on others as a way to have control and make themselves look better. Their insulting behavior has more to do with their own lame need for social recognition than it does with who you are.
Don't let them pick on you. Hold your head up high. You don't need to be in their group to be somebody. You don't have to dress like them, talk like them, eat like them, or act like them. They don't hold the license on coolness. (Ask anyone who's gone to their 30th High School Reunion.)
Next time those mean girls talk smack, ignore them or stand up for yourself. Try to get some friends to help you stand up against them. There is power in numbers.
You have more power and worth than you think you do. Remember: you aren't the problem. They are.