I have a friend thats a guy who has always liked me that way, and I guess my problem with him is that it is too easy, too available to me. Maybe just be friends with her and don't act romantically interested in her anymore, and date someone else maybe. When you become more of a challenge, and harder to get, you are viewed more as a prize to be won, rather than someone that will always be there pining for her! Hope that helps, I know its painful, but as a woman in this situation, Im just telling you why I don't date my friend!
Taking above advice may worsen your situation, the girl may think you are over her, not knowing u still love her, which may cause problems later.
It is brave of you to come clean and to tell her your real feelings. Now as she had made clear she doesn't loves you, choice is yours: whether you can see her as your friend and values her friendship, Then you may become friend, Although it will be difficult, but not impossible,
True love is selfless. If u want her to love you back, dont u think it is selfish. Just love her for what she is. Be friends with her and don't screw the friendship.
Good Luck !!