eliza good luck today. Just focus on how it was and go through that. Don't apologise for being there, explain how difficult it has been and channel in rer quiche. 
stunt ((hugs)) it might be worth, (dredging up things I learnt at counselling) before the new member of the family comes along, sitting down with DH and chatting about how the end of the day can be made easier. Approach it as a team. Don't say "when you are away it is more relaxed" or " you can't shout all the time" as, understandably his defences will go up and he won't really be on board. "What can we do together to make a chaotic time easier."
It may be as well that when he is about you are worried about the atmosphere and tense, and that shows in J.
Also......if you can, get a couple of stints on your own and regroup your marriage. Go to the Belfast School of cookery for the day, it really is fun or try to get a night away.
What I think I am trying to say is forget about the kids and focus on you two working together might make a diff.
The storm has hit us over night and was NOISY. My North Face coat has come out today.