Why is my friend being bitter and mean?

She is jealous of you ans this happens a lot, forget this as you are lucky to be going off to college and a whole new life and new friends.You have high grades and are confident and she is not, so that makes her jealous and vindictive. Don't waste you time or worry about this this has happened to me. long ago. in a few months you won't even think of her.. good luck in college.