In of two minds really. On the one hand it's harvest time and you knew before going. On the other hand you made it clear to your DH you didn't want to end up in the situation you're now in.
I would probably be more p*ssed at myself than DH and the IL's. I'd be thinking I should have realised this would happen regardless of what I'd discussed with DH.
Either way it sucks. Can you take the kids off somewhere else tomorrow?