"So its a husband problem. I wonder if that is the reason he split with the ‘problem ex wife’ that causes all the drama in the first place. "
Totally disagree with this.
I do the bulk of the housework in our home for two reasons 1) I enjoy pottering and keeping my home nice and 2) my standard of clean and tidy is very different to my husbands.
There's no disputing that this works for us but also there's ultimately a shedload more mess and chaos when there are 4 of us in the house than 2. Bathrooms need cleaning, the dishwasher needs emptying more. Weekly shops are bulkier and heavier.
If the OP's step children are quite a lot older than her younger child then there's a whole load more work to do.
My husband does the majority of the heavy lifting in the house, mowing the lawn, DIY, Ferrying our SC back and forth, taking the bins out etc. This morning he's gone to do our grocery shop. Whilst he gone I'm running The hoover round, putting a wash on and dusting. If the kids were here I'd be doing all of the cooking and more washing, more cleaning etc because he doesn't get to see them often so I leave them to spend quality time together wherever possible.
But on any normal week I'd be going to work, coming home and getting to spend about 3 hours a day with my husband doing things we enjoy. That doesn't make him an unfit husband. We just lead busy lives and both do the jobs in the home that play to our strengths.