Yes, he's controlling and yes, it's related to his ADHD as well as an inner sense that he has to have total control to feel safe. He is most likely totally unaware of his sense of insecurity and that he needs to have total control, even down to when to wash the sippy cup in order to feel secure.
I can respond to this from various view points. My father was much like this and his father, my grandfather, before him. I lived with my grandparents my first year of college and I was for the most part able to ignore my grandfather. My mother said he'd mellowed a whole lot with age. I was rarely able to ignore my father and nearly always responded in anger even after I became an adult and had years of therapy.
I finally realized that I was somewhat of a micro manager with my family after several years of counseling with my daugher and my husband. I was surprised years later when I was thinking about my life that I wasn't a micro manager in my career. In fact one of the reasons I left teaching was that I wasn't able to consistently manage a classroom to my micro managing department head's expectation. Quite a revelation!
I was for the most part an easy going supervisor as a police sergeant but I
had to consciously learn how to be consistent in managing. Learning a consistent, effective way to manage has taken me a lifetime and I'm still having to work at it. I resented my father's micro managing and in my careers went too far in the other direction, giving others too much latitude in carrying out their duties and then being upset when they didn't even do them.
At home, I vacillated between micro managing and expecting my children to know what to do. In between I felt a lot of anger because they just wouldn't listen to me. Learning how to be consistent is probably the most difficult lesson I've had to learn. Letting go of my anger over being micro managed and feeling unheard comes in a very close second in difficulty of lessons learned.
My daughter, to this day, (she's now nearly 30) does not like to vacuum because I insisted precisely how she was to do it and was angry when she didn't do it my way. I thought I was providing her with standards but my own anxiety over micro managing got in the way creating the anger. Looking back, I wasn't micro managing. I was providing a reasonable standard for what would be considered a good job. But when she didn't accept that standard I became an angry micro manager instead of just repeating the standard and having her redo it in any way that got the job done.
I am close to a couple who both micro manage each other and don't even realize it. If they're both in the room when they discover crumbs on the floor both will have a negative comment to the other and how what they did or didn't do caused the crumbs. Then they'll have a "fight" over who will clean it up as both of them start to clean it up. (They both want to clean it up.) It would be funny if the emotions weren't so raw. Both have been divorced and it's my guess that this attitude and behavior contributed to the divorces. What my friend tells me is that this marriage survives because they both realize that the other isn't going to change and they've learned to put up with each others' faults. They have frequent petty spats but still show love in between them.
It's my suggestion, based on these personal experiences, that your husband will not be able to make a drastic change. He will be able to modify his management style if he wants to do so. Wanting to do so will only happen once he's able to acknowledge that micro managing is not working for him. And I think that he probably won't be able to acknowledge that until he's able to acknowledge how his insecurity is driving his micro managing and then be able to accept feeling insecure. It's very complicated!
His insecurity triggers his micro managing and your insecurity triggers your feeling stupid. In reality, he's most likely not thinking you're stupid. He's thinking that his way is better and he needs to do things better so that everyone is safe. When he was a baby, a toddler, and/or a child he didn't feel safe. He doesn't remember why he didn't feel safe but he learned ways of behaving so that he would feel safe. As an adult he's unlikely to even be aware that he doesn't feel safe. He just knows that everything has to be done a certain way. He has to feel that he's in control. Tho he mostly likely won't be aware of his need to feel control.
I've been in therapy and it took me years to figure all of that out for myself. However, once I was aware that I was reacting to things from my past, I worked on finding out my triggers and dealing with them. It is a difficult process that takes years. For a marriage to survive they have to be in counseling and working together on this process. Both people have triggers that is causing them to react to each other in the way that they are reacting.
You can make your relationship with your husband better for yourself if you can focus on your reaction. Examine how his micromanaging makes you feel and find a way to deal with your feelings. You can't change the way he acts but you can change the way that you feel. If you can stop feeling stupid and angry he will be more likely able to recognize and then eventually acknowledge his own sense of insecurity that is causing him to act the way he's acting.
I suggest that the only way you'll be able to work this out is with intense personal and couple's counseling. It will help if you're able to let go of your anger at being micro managed. For me, my anger with my father was the source of my present day anger. Once my father became extremely ill and died I was able to let go of my anger at him. (That is a different post.) I was surprised at how not feeling angry with my father reduced the amount of anger I felt at other current times.
My daughter often micro manages now. I think the way we manage can be a generational thing just as parenting can be. I still sometimes get irritated with her when I see her micro managing her children. I used to try to talk with her about the way I micro managed and how she didn't like it and how she is now doing that to her kids and we'd both get sucked into rage. After my father's death and some more internal work I was able to feel more irritation than anger.
Now, if I'm starting to feel that I need to make a comment I leave the room and if that doesn't work I leave her home. You don't have that option. Micro managing is in your home. But you can find ways to deal with your feelings without reacting to your husband.
What will help the most is when both of you feel secure enough in your relationship that you can both tell the other how you're feeling and both of you can accept it without making excuses or rationalizing what you're feeling or doing. Isn't that what makes a good relationship in the first place? All too often we get side tracked with day to day living together and forget that love involves accepting the other person just as they are without needing to change them. OH MY!
That sort of love is difficult and takes a lifetime to learn if it can be learned at all!!!!! Sometimes it's best to let go and move on. It took me several failed relationships before I was able to accept that some people are just not able to show me the kind of love I want. Again, love is another very complicated emotion/relationship.
We all have boundaries set at a point inside of which we can be happy but outside of then we're unhappy. I finally learned that I cannot accept micro managing and I don't even try to have a relationship with a non related micro manager. I do work on my relationship with my daughter because rejecting her does not fit within my boundaries. I suggest that with counseling you and your husband will find what you can accept and what you can't. What you can change and what you can't. You'll find a way to be happy enough with each other to stay in the marriage or decide to find a way to have a workable relationship separate from each other.
At this point in your relationship when you're just discovering that he has ADHD, I recommend that you continue to work to find ways to deal with this including the micro managing.