Wow, that's crazy because your story sounds just like my own... I too was about 180 pounds, lost the weight over a period of about 4 or 5 years (and hit a low of 123 pounds), and now I seem to have lost all control. I think its partly because I have spent 5 long years watching every little thing I put in my mouth... and it just gets so exhausting. Sometimes it just feels easier to give in and have something fattening rather than struggling to be healthy, to count the calories, and above all to perform your best (whether it be at school, work, in a sport, etc) while you're tired out from losing weight (because it takes a toll on your energy level!)
Anyway the advice I have for you is something that I am discovering myself: I always think that I'll feel better if I give in and throw my healthy eating plan to the wind, but I don't. I've been doing that since Thanksgiving, and I've put on 6 pounds... I feel sluggish, gross, unmotivated, dissapointed in myself, and generally unhappy. The extra food isn't helping, it's making things worse. I know that its a "slippery slope" and it's hard to get back on track once you've strayed, but just keep in mind that overeating because you're stressed will not comfort you, it;ll only upset you more in the long run... and the more weight you put on, the worse you'll feel.
Hang in there!