I'll just go ahead and list the series of events and see if you can figure out if there is anything I can actually do or if this really is checkmate

Monday- After working on our project together after school and right before she is going to rehearsals I ask a girl out to prom and she says yes. She says that we can figure out all the details later and we hug after that. I wish her luck with her rehearsals and make my way home.

Tuesday- Things seem perfectly fine. We talk about how we might get to the prom and asks if I have a Facebook which I do and that I should add her on there to figure out the details.

Wednesday (today as of this writing)-  Right as 6th period begins she tells me she wants to tell me something I may not like. She tells me that before I asked her out to it that a friend and her were planning to go solo to it originally. She apparently told this friend that I had asked her out and I guess they came to the conclusion that it would be better to stick with their original plan. She asks if I'm OK with this and of course I lie and say it is. Toward the end of the class I ask if she is OK going without a date and that she is the only girl I want to ask to it and she replies by saying that she is sure.

I think that's everything that's important. So is there really a friend who she planned to go with originally or is she just letting me down and rejecting me in a different way? Do I have any options left?  I can't see anything I can do left except accept it the best I can and move on. Any and all opinions are welcome.