Well the good thing is that at least you have tried to say your feelings to her, but unfortunately in life often happen to get the opposite of what we think. I advise you at this point to do as she says; to help her staying friends; i guess it's hard for you to accept this thing, but if your feelings are not reciprocal, just keep on staying close to her as a friend, you can always look for another girl (i know between saying it and doing it, it isn't easy at all) with time i'm sure you will find another girl