Drink,drink,drink and drink some more!!!. Don't beat yourself up about it,you've done it now so move on, its in the past. Idid the same thing a few weeks ago,it was totm and I caved in,my son have left 1/2 a bar of choccie in the fridge, I was a bit peed off about something and lo and behold,before I knew it I'd eaten it! But rather than in previous diets where I'd think s*d it I've blown it now, I guzzled the water, brushed myself off and carried on (and still had a loss that week. Its a blip,it happens to the best of us, so put it behind you and you'll be fine.
Nikki x