If you have been feasting and binging for several days, or even weeks, the number on the scale may shock you. It's typical for clients to put on as much as 5% of their body weight (10 lbs for a 200-lb man). One female client put on 8% additional body weight (about 10 lbs for a 135-lb woman).
But most of this weight is probably from excess water retention, not fat.
Basically, the scale is lying to you. Realize that it takes a surplus of 3,500 calories to gain one pound of fat. Think objectively and without judging yourself: Do you think that you racked up that much of a surplus?
Possible, but not likely. In all likelihood, most of it is water weight. Take a week on a relatively moderate caloric deficit (20% or so) then step on the scale again so that you can come to an objective conclusion. Additional water weight should subside by this time.
Taking the scale at face value is particularly dangerous without doing the protocol above. I've seen clients who fell off the horse completely, because they assumed that they undid all of their progress. In reality it would have only taken a week or two to undo damage.
Often it's not the two-week vacation that someone takes that leads to their fitness doom, but the illusion that this doom had already occurred.
So analyze objectively, without judgment. Better yet, talk to an experienced coach if you don't feel like you can be objective with yourself.