OK, let me see if I understand. You guys are friends. At one point you both agree to Not Go Further Than Friendship. Then you decide to (I know it's an emotional thing, "decide" isn't probably the best word) Go Further Than Friendship. She doesn't want to, and you're upset/disappointed.
She's already gone a bit further in her head than friendship...she's more attached to you. The unusual thing here is that she recognizes it, and is strong enough to take steps to do what she already said (and you both agreed to) she was going to do.
I understand this hurts the heart, which really doesn't listen to logic. But if you think it's worth it, and can handle the pain of it, I say just be patient. Show her that you're not gonna flip out, pressure her, manipulate her, etc. But I'd also say give it a time limit. You don't want to be pining over the unobtainable forever, you know?
Good luck, and POST UPDATES! Please.