Friendship

Why is it so hard to find true friends?? Friends that don't talk behind your back, call you names, or get in a fight with you every week. I have a so-called friend that I have been friends with since kindergarten and she totally changed just over the summer. Now I just don't know how to explain her. She is so full of herself and thinks she's better then everyone. She puts up random fights with me like that she's stronger or she's more mature but seriously, if she was as mature as she says she is, she wouldn't be doing any of this. Well, I don't try not to gossip or talk behind peoples backs, so I guess I'm letting out feelings here. I don't know the right thing to do in this situation! Help!