OP, do you actually want to be with him? He sounds like a waste of space.
What I would do is add up his working hours each week including any commute time, and then add up your working hours each week including any commute time plus all the hours of childcare you do at times when he is out of the house including picking up and dropping off.
These are your real working hours that you are actually doing.
Then calculate how much it would cost to pay someone else to do all that work, including in the school holidays.
Spell it out to him.
He shouldn't be blowing up at you because he's just realised you "only work 21 hours a week". You should be blowing up at him for taking so little interest in family life and the childcare arrangements for his own child that he doesn't know how many hours you work outside the home. He should know this stuff. He should know how many hours you work and how many hours a week your child is in nursery and how the drop offs and pick ups work and how much it all costs and what the protocol is when the child is ill and has to stay home. If he doesn't know these things (and presumably isn't capable of doing these things if needed, e.g. if you got run over by a bus), he is not pulling his weight.
Back to the hours thing. Compare his working hours to your working hours (including childcare) side by side. How many hours are you each doing?
List all the chores that need to be done around the house including cooking, cleaning and washing, but also admin tasks.
How long do they take each week? And who does them?
If one of you is working (paid work or childcare) for, say, 10 hours less than the other each week, arguably that person should spend those 10 hours doing chores, and then anything else that needs to be done should be split 50:50 so that you each have equal free time.
Who has more free time at the moment?
I would bet a substantial amount of money that it's him.
And stop having his bloody dinner on the table at 7pm sharp every night! He knows where the fridge is.
Also, your financial arrangements don't sound very fair. Both your salaries should be going into one pot and all your joint expenses including mortgage, bills, food and childcare should be coming out of there. He should ideally be contributing a small amount of money to your pension as well, to compensate for the fact that you are working part time to facilitate his working full time, to his financial benefit and your financial detriment.
How dare he!
This has got me really riled up this morning.
I can't bear men like this.