I wouldn't worry too much about what your h thinks about you visiting w/his parents. If they invite you over and you want to go, then go. They still consider you a family member even if their son is a bit off his rocker these days.
He wanted to know what all took place because he was curious and realizes that he missed out on a great meal and also to see if he was missed/discussed by all. You handled this interrogation very well.
I do not think he's having a great time. He may act like it, but I don't think he is. If he were, he would sound more upbeat and tell you things w/o you having to ask.
He needs to realize that life goes on and it doesn't stand still just because he's not around.
Keep up the good work!
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.