Look, about the "bastard ex" thing, it is rubbish that he might not ever be co-operative, but surely a bastard ex who you only need to communicate with about your DS is better than a bastard husband that you feel you have to cook and clean for, that you have to share a home with, that you have to share finances with.
Is he going to do anything about the apparent 44 versus 444 thing to try and get the money back, or is he just pretending it was a mistake?
You and your DS deserve better than this. I completely understand why you couldn't think of anything you love about him.
You do not need to cook for him btw, I understand that you are trying to be 'fair' but he is not being fair with you - he is choosing to work extra hours, isn't showing you any respect at all by not even letting you know when he'll be home, and pissing the family finances away.
Please consider counselling for yourself to explore why you are so bound to being 'the reasonable/fair/nice one' that you feel that you have to martyr yourself making dinner for someone who can't even tell you what time he'll be home to eat it. Why don't you spend your time on a hobby, with friends, with your DS instead? Its not the 1950s, you do not need to run around after an unreasonable man, you can spend your time on yourself.
How certain are you that he spends those extra hours working?
Today is the 8th of October. There's an awful lot of month left. DH and I are on a single (not huge) income and sometimes the last week of the month is a bit tight, maybe the last two in January and we know we ought to organise our finances better. How appalling is your BH that he has f the family finances 3.5 weeks before the end of the month. Is he getting worse?