How should I handle being un-invited?

A friend from work, knowing I'd be alone this Christmas, said I could come to her house for the holiday if I brought a dish to share with her family and other guests. This was a month ago and she's been going on and on about how excited she was to have me come to her house. Then, just now, I got a phone call from her saying she's reconsidered her invitation - no reason given. When I tried to pursue it on the phone with her, she just hung up. Now I'm really ticked. It was bad enough being un-invited, but to give such short notice after I went and bought the things I needed to make a cerole seems downright cruel. I think she should have given me a reason as well as at least a dew days notice. What should I say or do when I meet up with her at work after the holidays?