I have a very dislike for this girl in my cl...?

OK, there is this girl in my cl well in my group of friends but none of us really like her, she is always showing off how rich she is, i always get into words fights with her i always win because i can out smart her but i am getting really annoyed with her, when i first told my group of friends who i liked she was there and the next day she was major flirting with him. I got real mad a wrote this mean thing that i probably should have but you know when you get mad you kinda over react, but then the day i wasn't there she was all "up" on him. Also today, she likes this boy who i really don't like also he is also very ugly and she was like " awww he is so cute, i want to go out with him, but he goes out with cindy" and i was like "ewww he is very ugly and cindy and him make a good couple so" and then she was like " umm no he is so hot and me and him would be a better couple" and then i was like " I can have my own opion about people, and if someone should go out with someone else" then she just turned bright red and walked off giving me glares. also once she told her mom about how i didnt want her to come to my party and her mom made me and her have a meeting to work things out but i really dont want to work things out because i reallly dont like her and she needs to reliase that. What should i do, i only have about 4 mouths left of her because next year i will be at high school, and proably be at different schools. So please help me