Sorry to hear you're finding it hard. If shouldn't effect it too much if it was a small slip and as it's only day 2, you might get away with it. You have to stick rigidly to it for the next week.
Can you identify what made you slip. Were you hungry, tired, thirsty, bored, peed off because you have to do it...there caould be any number of reasons I know but if you can see it coming in the future you can nip it in the bud.
The main thing is to stop beating yourself up and start again.
i have an awful cold and have been up all night with my 8 month old i just craved somethin sweet! i hope it doesnt affect my weigh in im so dissapointed in myself! will stick to it 100% from now on! xxxx