Ah, that does hurt... not just the price, but the fact that you did something you didn't mean to. That is what really gets to me! Big hugs to you and DH. :T
FWIW... it sounds like your friends do not ask for grocery money when they cook for you. And if A is as good a cook as you describe, then you easily got your money's worth in food alone over the years - forget the would-be hotel fees. And I don't think they were insensitive. They most likely figured they would help pay, and now they are having a very similar, how-could-you-let-that-happen conversation at home.
As a funny aside: I don't know about the Japanese culture too much, but Filipinos and Chinese have made stealing the bill into an art form. It is not uncommon to fight long and hard over the right to pay - and afterward someone might still try to sneak money into your bag on the way out.