I’m sorry your husband’s ADHD has been kept from you. My guess is he was ashamed and afraid of rejection, but still.
I don’t have anything helpful to add, but wanted to say that I’ve had the thought recently that I hope my son doesn’t have kids someday (he’s only 8). My son and I are a lot alike, so I probably have ADHD too, but he’s much more difficult than I ever was as a child. He’s like me but on steroids. So I hate to think what future generations might be like, and what he might put his wife through. I gather it hasn’t been easy for my husband to be married to me.