I thought Bridezilla behaviour was supposed to end after the wedding…

They’re being childish. Tried to throw their weight around through some artificially inflated sense of importance and had a tantrum when it didn’t work. Especially crappy behaviour if you were allowing them to stay with you, and after all the extra miles you went at short notice for the wedding. From your posts you do a lot for your family (it seems expected of you) and I don’t think this pair appreciates it.