Opposite bestfriend always try to compete with me.?

I'm a guy and my girl bestfriend always try to bring me down and just compete and god it pisses me off i get so annoyed. Like I told her i'm going to skip a grade from 10th to 12th by going to night school and the first thing she said was "Oh thats bad cuz your not going to see your friends ever again and its hard to go to nightschool" and I was well im going to get a scholarship for skipping a grade and i really need that money and she said "oh i doubt they'll give you money" I was "Uhmm... either way i wanna gradaute already" And its my last semester so i did skipped a grade. And I got a job at a restaurant and I told her how I am getting trained for a cook and that its hard and shes in cullianary cles in school and she said "Oh we already know all the basics and stuff and know how to cook" it annoys me why does she does this to me i would tell her how i feel but she scares me!