I know how tempting it is to fall back into the old ways of dieting - especially when the people around you are indulging. Maybe re-examine your motivation for wanting to lose your excess weight.
Personally, I couldn't stand looking at myself anymore. I got tired of sitting on the sidelines of my own life. I got tired of the self-loathing. Being ashamed of your body for 20 years takes its toll and it was time to stop complaining, stop hiding behind jokes and self-depreciation, stop punishing myself with food (you screwed up, you deserve to be fat), and start taking care of myself. I wouldn't stand for it if someone was treating me the way I was treating myself.
You are worth taking care of. I look at it like this - when I was pregnant I couldn't drink or indulge in the things that I LOVED (caffeine, sushi, martinis, eating mercury... whatever the current scare was ;) ) even though everyone around me could (and did). But I was taking care of someone (my child) and since she meant everything to me, I avoided anything that might hurt her for NINE months. *I* am as important as she is. Without *me*, I'm nothing. So, I think I'm worth at least 3 months of doing what's best for me and avoiding the things that have made this body ill.
Take care of yourself. Bite the inside of your cheek and suck down that unsweetened tea and repeat your mantra. "I am worth it." "I can do this." "I will make it through this day." This is not easy, but the results will be worth it.
Hang in there!!