Graciousness with oneself is a true gift and very often must be learned. So I'm glad to see you aren't flogging yourself unmercifully or wearing a hair shirt!
I am fortunate to live by myself and so I do not have to contend with families eating food around me. I imagine it must make things extraordinarily difficult because it's RIGHT THERE affecting all your senses.
From what I've read on this forum, much longer than three days and it's dangerous to eat solid food - so there's an incentive! But you'll be fine - as I've said to others, and HOpinso has said to you: you won't be the first to go off it earlier than you planned, and you won't be the last.
Fasting, like almost everything else, is a learning curve. And it sometimes takes a few times or a bit of experimenting in manner (in anything new), to find what works for us as an individual. IN the case of fasting, we are used to eating eating eating - even if we eat in a healthy manner, we're still INGESTING FOOD! The important thing is - you're doing it - even if you fall off the horse. You know - some people make the choice to not get back up, and that's not what you're choosing!