Spending more time together may kill our 35-year marriage

Due my husband's retirement and my current unemployment, we are suddenly sharing lots of time together.  We've been married for 35 years and I've always understood that his ADHD was an issue, and I've given him the benefit of the doubt for all of that time.  But today he told me that I can't start talking to him any more unless I'm sure he isn't thinking about something, or I can see that he isn't doing something - because it makes him very angry when I distract him and he loses his train of thought.  This came up because I asked him to quit being so mean to me when I try to talk with him sometimes.  I'm floored, and seriously wondering if we'll make it to 36 years.  Right now I'm trying to stay out of his space, and if I need to talk to him I go stand in the same room that he's in until he notices me and I'm sure he's prepared to hear me speak.  I figure I can do this for awhile, but I can see a day coming very soon when I'll throw in the towel.  I don't know if anyone has any suggestions, but mostly I just wanted to tell someone about this because nobody will understand why I walked away after 35 years.  Thanks for being there to listen!