Laura

First, I really sympathize with your husband. EricS had it right on the money about the different viewpoints of patients and caregivers. Jevity 1.5 is much much better for him than Ensure Plus since Jevity 1.5 actually does have fiber in it, in fact it's a special blend of oat and soy fiber that is chemically treated so after it hits the stomach it turns into 3 grams a can with 75% insoluble (what you need to avoid diarrhea). It's pretty cool, although it falls out of solution with wine so you can not mix the Jevity.
Hint to get more down easily: make a nice cup of coffee and add the jevity cans, they mix fantastic and the smell of the coffee plus the caffeine is a tonic. Of course this has to go down the feeding tube but it gets him in the habit of using it. For breakfast, I always have two full cans (474 ML) and coffee. For lunch, I do two more cans, For snack, one can in afternoon and then the Vitamix for real food.
Last but not least, please consider just telling your husband that you are counting on him to be here for you and the children. I know that if my wife had not broken down and said how much she needed me to tough it out and be here, I would not have bothered to do what was needed to be done. It really really hurts to eat, drink and the feeding tube is pure hell (still is for me). I've had a great and wonderful life and the struggle was simply too too much to deal with except that I realized that I would be abandoning my wife and son. As EricS posts, if you have a Why, you can do anything.
You can even do it tangentially by mentioning to him that when you read one post, you couldn't help but think that maybe he does not realize just how much you need and want him. Because if he does, then he needs to man up here.
Sad to say, what he is feeling is so normal, but that is no excuse for not dealing with it. Oh, and despite what everybody says, if he gets 2,000 calories down a day, he will make it. I was only 56 kg when I ran marathons and I am taller than your husband so his weight seems okay to me especially since I went down to that during my first TX.
Charm