talk to gp, you can get counselling free on NHS, though there's a waiting list
write him a letter if talking ends in fireworks, and ask him to do the same.
you must reassure each other that however difficult life is right now you are in it together. that feeling of safe, might ease the tension to start with.
remember, you love each other, so try and apologize and forgive.
try and use humour as an aid to defuse stressful situations,
could you work out a little rota at the weekends when one of you have an hour or 2 to sleep/relax/pursue a hobby while the other takes care of kids? then swap.
I know that tiredness makes everything look so much worse!
Also I find a walk after Sunday lunch is a nice time to reflect on the week gone, the week ahead, swap ideas, work out short/long term plans.
It's a good time to reconnect, have time for each other while the kids chase each other.
And don't go to bed angry.
I was once furious with DH just as he was taking boys camping for 5 days and the argument would have gotten even bigger if he had stayed. but I just couldn't let him go like that so, I said that although I'm still angry I'm happy to forgive him in advance until I actually feel that I can forgive him. it worked!
I actually stopped feeling angry just by saying that I would!
you can forgive him, no matter what, even he's not "sorry", so do it!
forgive him and yourself.
you can work it out and you can be happy.