Tired of being punished but not gonna quit!

I'm tired of being punished at the scale for having an impulse indulgence of a snickers bar! I'm not saying this because I want to quit watching my weight altogether but it still irks me that when I have a moment's weakness after skiing down a few slopes and purchase a candy bar and eat the whole thing, the next morning I stand on the scale and it seems as though it cost me 5 pounds!! What the heck??? I know a lot of people have this same problem but it seems like it doesn't phase them at all. Why, when I'm consciously trying to watch but at the same time allow myself the occasional goodies, do I have to watch the scale go up instead of down after all the hard work that I do 95%-98% of the time? You see that the percentage isn't right at 100 because I do have to give in occasionally for myself to stick with the plan as long as I fit it in but most of the time, I'm careful to avoid all the wrong things at restaurants and at home (i.e. creamy soups, too much salad dressing, breaded entrees, etc...). IT'S SIMPLY NOT FAIR!! It's times like these where I wonder why do I even care? Well, I've come too far to quit now but it's just a sobering thought to know that if I ever quit watching in the future, that I'll just go right back to where I was and it would be even harder to watch without that constant support group that I have every weekend. I would have to work so much harder to keep the weight off without the tools and the constant reminder that I have to weigh in to keep myself honest (since being a lifetime member, I don't have to weigh in every meeting--just once a month at least) but I keep tracking my food intake and weighing in as I did when I first began because I do want to lose about 10 more pounds or so. Why do the last 10 or so pounds have to be the hardest then?