People absolutely can be married and be on completely different diets. It's not easy but it can totally be done.
Frankly, the fact that your H likes mac and cheese and spaghetti-o's is very in-line with his behavior in that text exchange. He's acting like a child. I'd ignore it. Pasta is cheap, let him donate it or find someone else for it to go to. He could have texted 100 other people about his not needing the pasta but he texted YOU. He pursued you, you responded and he pulled away with his "it's not your business" crap.
I'm not you and I'm no vet but he's acting younger than my D6. I'd NC big time. I wouldn't want to be his mother.
The bulking up thing is very indicative of him trying to up his sexy-factor. Douche.
