Aww, I'm sorry you are feeling down about what she said. Don't worry, one day you will be best of friends and she will appreciate all that you have done for her.
I'll admit, when I was her age I was a rotten little b*tch to my mom. I think it was from about the age of 14 to 16. She still reminds me of the time I said "You are SO pathetic!". I'll never live that one down. I'm 25 now and thankful for the lessons she has taught me and consider her a friend, and not just a mom.
