Trust me...I understand the self-control issue. But as someone who has been (and likely still is) addicted to sugar and high carb foods, it's not just a matter of self-control. It's an addiction. I also know how hard it is to get past that overwhelming craving for sugar...been there, done that, lost a few rounds.
Keep encouraging him to make small changes...maybe cut out sugar first (hey...why not replace that regular ice cream with CarbSmart...tastes just as good! ), then another change and so on. Some people find it easier to sort of "slide" into low carb by cutting back on carbs gradually...say first to 150 grams of carb, then 100 and so on. He may find that he loses well even at 100 grams of carb a day...you never know!
As my DH is fond of saying, "It's better to have tried and failed than to never have tried at all." and "Often, the only difference between those that succeed and those that don't is that those who succeeded kept trying no matter how many times they failed."
Keep reassuring him that you still love him and that you're not going anywhere, but at the same time you can encourage him to give it another try....if for any reason that you'd like to be able to spend a lot more years with him.