Hi C.. I'm sure a lot of it is cultural, and also he's the baby of the family, and now he has a baby himself and may be freaked out a little. Was this something he did before you were married? If so, it's not a surprise, and though you are understandably upset by it, you had an idea of what you were getting when you married him. Americans are a bit wierd in that we have this nuclear family thing going and can't quite figure out how the huge family dynamics work. Like you said, that could be part of the issue.
That said, perhaps (if you have a pleasant relationship with his family) you and the baby could spend more time with his family for several reasons: extended family is VERY good for kids socially; also, very good for MOMMY when she needs a break!, and he will feel better if you are there as well. You may be able to build a relationship with his mom where she can help you when she notices stresses he has that he might not be able to share? See if you can visit when he does sometimes. Everyone go over on the weekend - bring some dessert and make it a family dinner night. Considering you had the illnesses in the very recent past, it would be good to have a family support structure for yourself, and you might be more blessed than you know if you can navigate the culture shock :)