It seems like you’ve been let down by the professionals early on, this may have caused your spouse to lose confidence.
Anyway, my partner is undiagnosed but obviously ADHD. My journey in educating him and eventually getting him (and our family) diagnosed, helped and treated began 3 weeks ago.
It’s going slowly but I’d say in the right direction.
I bought a book called “so I’m not lazy, crazy or mad” and I gave it to him. I said something simple like- “look babe, this book is about you! I’ve read it and I’m sorry I keep shouting at you for not putting the trash out” then I gave him a hug and left it on the table.
Then I bought a book, “smartest boy in the math class” when he put our son to bed on the weekend I produced it and it was the bedtime story.
Now, I say things like -“babe, you’ve zoned out on me again!” And I laugh.
Our life has become easier because I understand.
I gave him a storage box with a lid for his cycling clothes and he didn’t say anything but I know he’s happy now it’s organised. At least he won’t accuse me of hiding it anymore.
I find articles online describing his struggle, screen shot them and email to him. I’m doing all the work, our trash is still stock piled and attracting rats but I’ve taken action.
I cannot change him but I can change myself. He hates me a little less now I’m more understanding.