My best friend is dating my crush. What do I do?

Okay, so I like this guy, Curtis, and so does my friend Sarah. So when he asked me out I said no, because I didn't want her to be sad, or mad. But he asked her out a few days ago and she said yes. Should she have done the same thing I did? To be fair? Or, is she doing the right thing? I have cried the last few days, and all she said was, "Well, I guess I got him first." I couldnt believe her, but am I overreacting?