What a situation
I know we all want answers for ours pets demise, and sometimes it is poor quality foods, but there are so many great high quality cat foods on the market now, that maybe with your cats being so ravenous, a good quality dry cat food left out at all times will help with this situation.
My oldest cat passed away this past September and he was 19 years old! he ate good quality dry food (available at all times to free feed) and canned food in the evenings. I also have 4 other cats ranging in age from 12 to 15, all fed cat food. I have also had a cat die at the age of 7 due to liver failure, so it's really difficult to blame cat food on her death.
I understand where you husband is coming from, it's very difficult to enjoy your pets company when they become such a nuisance, I believe free feeding your cats a good quality dry food, and teaching them some manners, would go a long way. I know you probably love them just the way they are, but if they are as bad as your husband says (you know what they say, love is blind) you may be depriving yourself of human companionship, due to their unruly behaviour.
Please don't think I am to harsh, I am trying to see all sides here (yours, your hubbys and your cats)