"I thanked his aunt for the great supper. I didn't realize she expected us to pay for our portion of the supper

"
I have never heard of anything like this! His mother sounds like a world of trouble, but at least you know that tacky cheapness runs in the family.
I'm surprised she didn't ask you all to split the cost of dishwashing detergent and water because she would have to wash the dishes you used.
I was married to a "mama's boy," and those ties never loosen. A real man loves and respects his mother, but his woman comes first.
I smell trouble honey bunch.