Ya know what, I'm on day 4 right now and there hasn't been one night that I haven't thought about cheating. In fact, almost every night I've had dreams of eating pizza, burgers, potato chips... you name it. I haven't eaten that stuff since January... so there's no reason to be craving it.
The point is... I think it would be VERY easy to cheat a little. Each night I think it's the last night I'll be able to do it. I'm lucky in that I've had LITTLE stress at home otherwise I'd be right with you.
Don't beat yourself up... I'm no Master-Cleanse expert, but I'd say if you have the willpower get right back into the groove and continue on. You started the program to get healthier or perhaps lose weight. If those are still goals... then you owe it to yourself to keep going. As with most things in life I've found persistence pays off.