Don’t try to be friends with her then. I know it’s hard, and she doesn’t have to be doing anything wrong for you to be justified in doing that. Maybe even explain to her very plainly (and not in an emotional or distraught manner) that you have romantic feelings for her and for that reason you don’t think you can see her as friends. I know that sucks too, but it’s honest advice and I’ve been down that road and trying to be “just friends” with somebody you have romantic feelings for will multiply both your feelings and your pain, and while it may hurt now to cut her off trust me down the line you will be hurting more. Find somebody that is actually interested and you will be so much happier with everything.