I'm sorry to hear are not going as well as you'd like them too. I always thought a baby changes a marriage either for the better or the worse depending on how the marriage was before the baby.
Men usually act one of 2 ways, one, they're gushing over their wives when they're pregnant and their sense of respect is renewed right after labor because of what a woman is capable of doing, bringing a miracle into the world. Two, the totally go the other way. They become despondent and you never see them. I'm sure your husband loves his son, I don't doubt that for one minute. My first impression from reading your post is that he's stressed out because now there's a little baby who is totally dependent on him and you for everything. This is new territory for him and he's not sure what to do. This is one of those things in life where you don't get instructions to follow. I know most men like to throw away the instructions (LOL) and figure it out, but they can always retrieve it and read. This time, there's nothing in the garbage to retrieve, even in secrecy and pretend he did it all by himself. :-)
Do you have someone that could watch the baby for 2 hours? This would be a good time for both of you to sit down and talk about how you feel. No one is to blame here, just 2 people who handle things and see things differently. Don't look for hidden meanings that either of you thinks the other one is a failure. That's not true. Make some compromises, work together. It took 2 people to make a baby, it should take 2 people to raise one together.
I've been married almost 10 years with 3 little kids and what I would give to marry my husband all over again. Both of us are peacemakers so we give in too easily when we argue. We tend to look at the arguing/nit picking not as being mean or hurtful, we look at as a learning, brainstorming discussion. Think about it, if you never argued, how much would you learn about your bf/husband? It's ok to disagree at times and it's ok to leave it at that too.
I agree counseling would help too even if only for just a few sessions just to get it all out and lay it on the table. If you're both committed to each other, then it will work out and it doesn't have to be perfect by anyone else's standards except yours and his. :-)
Best wishes to you both. Your baby needs you both and loves you even though he can't talk yet.
Mary