My twin sister is better than me.?

my twin is really mean to me. she tries to compete with me for everything, weight,soccer, grades. she always wins. We have the same group of friends and goes to go hang out with them without asking me to come to and ditches me. she is getting over anorexia too. my mom gives her everything she wants and never punishes her because of her anorexia. If i try something new, like a new hairstyle, she points and laughs and tells everyone how stupid i look. Everyone thinks she is so nice and sweet but she is not. she throws hissy fits all the time and is a ***** to my mom. I dont know what to do. i have no friends and i know i shouldn't compare myself to her but i cant help it. were twins. please help.