Is it normal that i hate my best friend?

I don't know what is wrong with my, so called best friend. I have know her since 4th grade. The only reason I play with her, is because she plays with my two best friends. They are my only friends, so I just have to deal with her.

She is always complaining that her life is hard, when she gets everything she wants. Last week she got, no joke $10,000. And it wasn't even her birthday or Christmas. Her parents spoil her with everything she ask for. The funny thing is that her parents think that she is the smartest in the grade, but she dosen't even know her 1 timetables (WHAT!!). She is always in the lower groups. She thinks that she is so funny, and smart.

She is forever bragging on about how on her birthday she only got a plane ticket to America, England and Italy, if I got a plane ticket to America, England and Canada, I would be forever grateful of my parents. If I was her I would respect what I got. When I went to her house, there is one room filled with all her stuff. Her brothers have no space to put any of there stuff. She always thinks that her brothers are annoying, but she is just like them.

Once I played with these other girls, because I started getting sick of her, guess what she did. After school she punched me in the face, and kicked in the leg. And she pretty threatened me not to tell anyway that it was her who did this, or she would do it everyday.

I don't know why my other friends think she is cool and dosent realise who rude and spoiled she is. I really wanted to tell how I feel about her but I just chicken out.

What should I do?