Is that really that bad... we had a party...?

No. With as much excercise as you're doing you can afford to let yourself go everyone once in a while. Focus on portion sizes. As long as it was one piece of bread and not ten pieces. Don't beat yourself up over one night. Have fun with your diet and you'll lose more weight than if you're stressed out all of the time. If you're worried do an extra set of situps.