Try to focus on you and the children only. Make sure you and they are clean and fed. He needs to start fending for himself and more importantly, being a husband! He lives there too, it's not all on you!! You are a team, he needs to realise that and do his bit and take the load while you're poorly.
If he's doing this now, how will he be when you have the surgery? Don't feel guilty for his inaction. Let everyone, especially his mother, see how he is and as people have said, if she says anything, flip the responsibility on her for not raising a thoughtful man.
How does/did his father behave when it comes to housework and the running of the home? It may the patriarchal home he was brought up in so he sees it as your "role" and his mum was a submissive, sorry, dutiful housewife, so sees no wrong in her darling son's behaviour as well?
Hire a cleaner! If it helps you feel better down the line when the surgery is done- do it. Why is he getting final say? You can make household decisions too.
It'll help you both, even if you book services short term. Yes, it's a get out of jail card for him, which is annoying, so leave it a while and see if things improve. If not, do it for your wellbeing. You deserve that.
Hope surgery goes well when you have it. Hope you feel better soon!! X