Your standards for eating during pregnancy are far more restrictive than average and so you should have mentioned this before you got there. If your husband isn't prescient you should have prepared him that you'll only eat a very limited menu and that he should notify his parents to have something on hand that you'd be willing to consume. To wait until you got there and expect people to have read your mind is a bit extra. Most people aren't super comfortable around their in-laws, that's normal. But if you're going to be on such a strict diet you need to let people know (before you show up at their house). Next time maybe just bring your own food so this doesn't become an issue.