Spouse deep in denial despite diagnosis

I am looking for some support and answers regarding diagnosis and denial.  A psychiatrist diagnosed my husband a few years ago with ADD yet my husband is in deep denial and refuses to seek treatment or see how his behavior affects others.  He believes he is "managing" just fine. After many arguments and broken promises, I felt I had no option but to enable him by taking on the finances, children, home, calendar, estate planning, investments, initiating sex, planning time for us to be together, etc. Many of these tasks cannot just go undone.  (I am a former English teacher and he is an attorney, he truly is better suited for some of these tasks.)

I became exhausted, lost my self-respect and lost my identity as "an equal." I became angry and bitter. In recent months, I have taken a different outlook.  I try to see my actions as self-care should I decide to leave him.  I must oversee maintenance on our home - or I won't be able to sell it when I leave him.  I must take care of the finances so I'll be able to get credit when I am divorced, etc.  This may be good "boundary setting" but it is lonely, unsatisfying work.  I have no hope for our marriage. Yet deep down, all I really want is to feel part of a team!

When I try to discuss my feelings of loneliness, disappointment and frustration, my husband passive-aggressively denies any responsibility.  He simply states, "I hear you saying that I am the sole problem.  You think I am to blame for all our problems."  He is very good at getting me on the defensive.

He recently agreed to go to Dr. Hallowell's seminar in June.  I thought if I could get him there, he might finally see the light.  Yet today we talked and he stands firm that I cannot demand he change.  He believes that since I married him the way he was, he is not obligated to grow or change. 

If he had a vision problem and couldn't see the road, I think it would be plausible for me to demand he get his eyes checked and get glasses if that's what the doctor ordered! Living with a spouse with untreated ADD, I often feel anxious and fearful like a passenger in a car with a blind-folded driver.  I don't feel safe and secure. I never feel we are on course. Living crisis to crisis has taken its toll on me.  I am a stay-at-home mom raising three young children.  In many respects, I have put my life in my husband's hands.

Is it fair of me to of give him an ultimatum?  "You must get treatment for your ADD or I am leaving you?"  I need advice because sometimes I find my strength waning and start believing I am being unreasonable.  In many posts, Melissa talks about supporting the ADD partner in his treatment.  I can't support denial.  I can't go on living this way.  I am so lonely and desperate for a partner in life.  I know I can't change him.  I know I can't make him want to change. 

1. Don't spouses/parents have a responsibility to get the best treatment for their ADD once diagnosed?

2. What benefits does he get by remaining in denial?


Thank you! 

PS:  His ADD was not evident when we were dating.  It was a "novel" time in our lives.  We had no dependents.  We weren't home-owners.  He didn't have a track record of broken promises.