I think understanding that he is experiencing stress at work and probably expressing stress due to other factors at home...new baby, money, etc is the first part of the battle.

Firebombing you and then secluding himself may not work well in the long run. Help him explore a more healthy way...maybe he can have a method of decompressing between work and home. I struggled with this transition a lot...I overdid myself so I could be at home at x time only never to be really present when I got home and I was poorly equiped to handle things that needed to be dealt with at home.

When baby comes more stress will be present as you will probably "need a break" when he walks through the door...so I guess I would help him discover ways to better transition so he can be present..

Does this make sense?