Wow, I'm so sorry. That's absolutely awful.
In the grand scheme of things though, it's just one birthday. You'll have a lot more, and much better ones, I promise.
In the long run, you probably don't want to be with a girl who will believe people's lies and not give you the benefit of the doubt, without at least talking about it before storming off.
I've always felt it was better to be alone than to be with the wrong people.
Since the party didn't work out, perhaps you could schedule another one? Maybe next week as a post-birthday party?
Anyway, for what it's worth, happy birthday!