Need help! Husband in denial about ADD

My husband and I have been married for 15 months.  He is a wonderful, kind, caring man.  He is just so forgetful and disorganized.  I have to tell him what to do constantly.  He cannot for the life of him, straighten, clean, or help around the house without guidance.  I did not know all this about him when I married him.  Everyone should live with a person for a little while before they marry them and then there wouldn't be this problem.  He has been driving me crazy the whole time we have been married.  He forgets whole conversations that we have had.  He is the most disorganized person I have ever met.  The house that he lived in before we were married was the dirtiest house that I had ever seen in my whole entire life and he told me before we got married that he was a neat freak and cleaned constantly.  There were clothes piled and strewn everywhere, mouse poop underneath the stove, the microwave was so dirty it had to be thrown away, papers piled everywhere.  It was terrible.  So after 15 months of this, he calls his mom who tells him that he has always been that way and that he has ADD and she has it and his aunt has it.  So of course I think "bingo, that explains it all."  The next day, he says "Oh, it isn't that bad.  I'm just a little forgetful."  I call and get him an appointment with a counselor and he forgets his appointment and has to make another one.  He does not want to take any responsibility for any of this and I would so hate to hear what he is saying to the counselor.  We are going together later this week.  He has irritated me so badly that I can't stand the sight of him any more.  He adopted my 8-year-old daughter and she loves him so much.  I just don't know what I am going to do any more.  The counseor wanted him to be checked out by an MD to make sure he had no underlying medical conditions that might be causing all this and the doctor just took his blood pressure, listened to his heart and said he didn't think anything was wrong and that it was just stress causing his forgetfulness and everything.  I told him he had it backwards that it was the forgetfulness that was causing the stress.  So the headaches, dizziness, numbness and tingling and all that that my husband also experiences was felt to be nothing.  I so need help.  How can I make this better if my husband won't even admit that he has a problem?  And how do I get my daughter through this if it comes to divorce?  She loves him so much and wants him here everyday.  Thanks in advance for any advice.