Actually I think you're achieving an amazing amount with a 4mo. Staggering in fact when you consider that she is clingy.
What exactly has prompted his change of heart? Is it driven by money? The fact that he is saying that you're being abusive when you stand up for yourself makes me think that he is actually trying to control you. Appreciate that I could be way off base here.
The Organised Mum is brilliant, my house has never been cleaner and it also changed my life. I'm not sure I'd suggest it with a 4mo though (and I've been recommending to everyone), especially one who is clingy. The 45 minutes are intense and if you break the sections down into chunks then those chunks can be intense and you can feel like you're spending the whole day cleaning. I am currently 38 weeks pregnant with a 2yo and finding it a struggle, although determined to keep it up (so DH can take some on when he's on paternity leave). I did a bit of deep cleaning in the lounge yesterday - according to the organised mum it should have taken me 45 minutes but it actually took me 1.5 hours because I had a 2yo helping and I imagine a clingy 4mo would have the same effect. You might however manage the 15 mins a day section which would keep things clean on a very very basic level.
Here is my schedule from when DD2 was 4mo:
Monday - washing
Tuesday - paperwork
Wednesday - Hoovering
Thursday - Change beds one week and dust the next
Friday - Deep clean kitchen one week and deep clean bathroom the next
Saturday - batch cooking and more washing
Nothing was ever all clean at once but it worked for us. Then some weekends we'd pull the sofa out and clean windows etc. I say WE.
Can you get DC1 to help with stuff? My 6yo actually asks to hoover and wash windows etc. DD2 used to nap lots in her sling and the only things I ever really did with her in it was load the washing, wipe down kitchen sides, make breakfast/lunch and prep food for dinner. Anything more would have woken her and I don't think I could have physically managed it. Saying all of that my overall feeling is that you should keep the cleaner. If it's a money issue then you and DH split the homework. Sorry but expecting you to look after the children, "keep a house" and facilitate his hobbies shows that his priorities are seriously out of whack. He sounds incredibly old fashioned. Have you tried writing out what you do in a day for him to see what it's like...or filming it? He's not listening to you and you need to find a way to make him. Frankly he can't make you clean and in your shoes I wouldn't. That would be an interesting turn of events!