How can I protect our dog from my husband's obsession of feeding him?

I know this may seem like a relatively unimportant problem, but husband has always fed table scraps to our dog, who has always had a very sensitive digestive system. Before his dementia he was reasonable -offering him an empty ice cream bowl to lick the sides, or an empty milk glass or a plate after finishing a meal-allowing him to just "clean the plate". I never approved, but because he was not really giving him food items I tried to keep from constantly objecting and causing conflict. Now, however feeding table scraps to our dog has become part of a "jealousy" thing and it is now one of those obsessive behaviors that many times results in much agitation. He wants to feed our little guy anything and everything he has and today he went to such lengths to hide it from me that I was shocked. I have asked him, after he gave our pup a piece of his sandwich, to please not give him anymore. He invited the dog up onto the sofa and casually reached down, as he though I was not looking, giving the dog another bite. I said, and in a calm voice, "no, you must not give him food". He then waited until I was focused on my iPad and carefully reached down to the dog, again giving another bite, but hiding his hand with a pillow. I picked up the dog, saying nothing and took him to the bedroom, closing the door. Soon I thought he was finished with his munch so I picked up the dishes, taking them to the kitchen. When I returned, I saw that the other half of sandwich was now in his hand and I apologized for taking his plate before he was done. He said that was "ok". I went back to my iPad. He then got up, I thought, to use the bathroom, and as I had asked my son to sit with him while I tried to take a nap, I headed for the bedroom. The door was closed and when I opened it there was my husband feeding the dog again. I made the mistake of trying to explain to him that these foods are not healthy for the dog. He walked out with the remainder of the sandwich and into the bathroom. I laid down, but thought something was fishy, so I went to the slightly ajar bathroom door just as he wrapped the sandwich in a Kleenex, placing it in his pants pocket! Once again I tried to explain how this was not good for this dog he loves so much and asked that he give me the Kleenex wrapped food. He was angry, but he did. I tried to talk with him about why this food hurts the dog, causing vomiting and diarrhea, but he does not believe that even though I have shown his the puddles,  then went on my iPad to look up foods never to give to dogs, to show him and the explanations of why. Ok ok, I KNOW...you are all thinking "why is she thinking he will understand or remember that?" I was desperate! He went to such lengths to hide the sandwich and sneak it to our dog-I went a little crazy and thought I could make him understand. I always try to tell him how both pets have special diets and their food is balanced just for them. But this is part of his obsession about both our cat and our dog. He insists that they are both"his" and insists that they be with him, either on his lap or next to him-to the point where he holds onto their collar nearly choking the dog a few times. He accuses me of planning to kidnap them at night, and on and on. I am so open to better ways to handle this. Please help! Today has been the worst ever. Though he was able to read the well illustrated article I showed him, he was certain that it just was not true.