Has your husband observed your kids with other ND kids their age? That's the thing that drives the point home for many people. If all you know are your kids, it's easy to stay in GT denial, as in "Well, they're bright, but they're not THAT bright. They still do X wrong." Only in context can most people see the reality of life for an HG+ child.
Is your DH someone who needs to research or not? I am, so I totally get where you're coming from. But not everyone is. It sounds to me that it may be less that he doesn't get your kids and more that he doesn't get your approach. That's actually easier to deal with, I think. But I realize I may be way off there...
