Who's billable hours will DH be using, to write up your chores list ?
I can't help thinking your husband isn't working to capacity if he has time to do this.
After 15 years of looking after 2 children with varying degrees of needs, I am completely burnt out. I am still looking after one of them to a large degree, but in terms of pure logic, I could start work again, outside the home at least 2 days a week, if not 3. But I can't. DC has very random needs, but more importantly, I am screwed. Physically, everything has started to go wrong, and mentally I'm a shell of what I once was.
DH has said I should go back to work if I think it would help (he knows I find work a doddle by comparison), but otherwise, is completely fine with me taking my time to see how the future plays out.
Early on, he made some remarks about wanting to be the one at home (although our once equal earning powers had already diverged dramatically), and so I took him through the logical steps of explaining what that would involve. He realised that actually he'd rather be the breadwinner, and that hasn't changed in 12 years.
I see this over and over again, men get to a stage where they're successful, start to believe they're somehow a little more special, and little more important, and start to resent their sahw.
Not because they're lazy, but because suddenly the job has become less essential, and they forget that just 18 months earlier they literally couldn't function without their input.
Yes, he could farm out childcare, even cooking, definitely cleaning and "concierge services".
But does he care about what he is losing in terms of a partner, and the mother of children? Have they got to a point where their marriage is purely transactional?
I think after raising 3 children to this point, in my experience, there is every reason to have a few months of slightly less constant responsibility. But at some point, for her own self worth (and frankly, with this twat, essential) I'd suggest starting some studying, upskilling, retraining.
Then, once the youngest is at school, you can find a job, and start paying for wrap around care, cleaners, gardeners, etc etc.
Let DH know the costs involved, and that they will be coming from your joint account.
Also, let him know that, as he is earning 5x? 10x? your new salary, you will be contributing pro rata, 10% or whatever of your salary to joint expenses, and the rest will be going into your pension.
Good luck.