Hey, lady!
You are a pretty amazing person and you have made some wonderful changes in your life. I get the sense that your guy is kind and generous and reasonable. I think that you are doing all the right things---setting an example, being honest about your concerns without being pushy, and recognizing how important it is to have a healthy family.
I have become quite adept at making meals that fit all of my family's needs. I make a protein, a veggie, and a carb, and people eat however much of whatever they decide. But if the family decides they want to grill hamburgers and I do not want red meat, I'll steam some fish or something. So we don't always eat the same things, but I stick to my plan most of the time come high or dry. I know what I need to do and I do it.
I think you could sit down with the family and come up with some meal guidelines---like veggies are nonnegotiable. It's great that he makes dinner, but there should be plenty of veggie servings (I don't count corn as a veggie, but hey he's trying!). Maybe make up a weekly menu with everyone's input, and then you do the shopping and edit the ingredients. Like meatloaf---half ground turkey, half ground beef (cheese on the side!). But get everyone involved in WHAT to eat, but you buy for it so you can control the health of the ingredients.
I know that if my DH would have commented on my weight or health before I lost 50 pounds, I would have been devestated. But you have really brought up some very serious concerns about your DH's health. Find a time when you guys are alone and relaxed and have a heart to heart, but keep it kind and loving.
Other than that, I can't think of a darn thing. I think you are doing everything I would otherwise suggest.
PS Maybe check out that Hungry Girl cookbook. I haven't read it, but I think she has healthy versions of "junk food". Maybe that would keep DH happy but also healthier.