The more you build it up, the harder the fall is going to be. You think the only reason she could have asked you who you like is because she is interested in you? Women enjoy wondering and predicting about social intricacies and why people act the way they do. Most likely than not, she wanted to know so she could add one more bit of information to her social dossier and since you are her friend, she could ask you openly. When you kept refusing to answer, that only heightened her curiosity.
For the sake of argument, what if scenario 1 happens? What are you going to do then? Are you going to forsake your friendship with the guy just for her? Would you steal your friend's girl, or sit there and pine after her until they break up and then pounce?
There is no reasonably positive outcome for this scenario(unless your friend become an unreasonable *** all of a sudden for any number of reasons, in which positive outcomes open up for you). Because of all the variables involved, when you told her you liked her you set yourself down a road where you will lose something no matter what the outcome is. Best case: Things become awkward for awhile, but eventually you both get over it and you can get over her and you two just laugh it off like a joke(possible, but I'm not putting my chips on it). Worst case: She cheats on her bf with you or leaves him for you, in which case you lose a friend, or she only likes you as a friend, her bf finds out and not only do you still not have a chance with her but you lost a friend as well.
I know it sounds like I'm trying to beat you down with pessimism, but I don't want you to hype yourself up so much that you become a shell of a person when the hopes you've invested so much time and emotion into come crashing down around you. And it's likely they will in one way or another.
Democracy: rule by the stupid