I might have a wee insight that could be helpful as someone with ADHD, although it's known to manifest differently in women.
For one thing, I'm very rejection-sensitive, so when anyone tries to bring up an issue with something I've done or am doing, I struggle not to take it personally or get defensive. That's been flagged as a common ADHD issue, and when trying to work or co-parent that's a huge stumbling block. I recently had a falling out with a friend who also has ADHD and we didn't speak for months because we both took it very personally and had a hard time admitting we'd done something wrong to each other. In the end we had to agree to just act like it never happened and there's still some strain there, but it's better than nothing. I find the phrase 'it's not personal, I'm trying to help you' is very helpful both to say and to hear.
I'm also very conflict-avoidant, because I'm afraid I'll end up saying something horribly cruel if I'm in a fit of temper. I refer to it as having a brain-to-mouth slide, the thought is in my head for a second and then it slides out of my mouth and sometimes it is vicious, and because it's an intrusive thought that I really don't mean (there's an overlap with the likes of OCD and Tourette's) I upset the person I'm arguing with, so I just try to avoid any conflict full stop.
There are concrete things to manage day-to-day life, but the real issue is getting the person with ADHD to actually engage with them. My mother gets me calendars and diaries constantly to help me stay organized and I never use them, I put them down and when they're out of my sight they might as well be gone forever. I have a cork board and fridge magnets so if I have appointments the letters go straight there where I can't miss them, and I have sticky notes all over the house. That works for me, but there was a lot of trial and error to getting to where I am now.
I used to work in childcare and I was excellent at it because it was instinctive to me, but what really helped was that parents used to leave detailed lists on the fridge or counter and I'd refer back to them throughout the day. I know it would feel strange to have to do this for the other parent of your children, but he might actually be relieved to have it.