behavioural changes - what to do when your husband refuses to make them?

My husband has been diagnosed for 18 mths. He takes ritalin and it has helped a lot - he also exercises and has quite a healthy lifestyle... but he adamantly refuses to make any behavioural changes. This means he still forgets what I say, doesn't follow through on agreements, rushes off in all sorts of directions (we are rennovating our house) causing no end of havoc and wasting time and money.

We talk through what might help - including writing things down, always consulting before deciding etc - he does it petulantly for a day or two and it quickly goes out the window.

He says making these changes would be 'stifling' that it would mean he would no longer be himself - he doesn't see why he should have to adapt to a world that he thinks should work better for him!

I'm really stuck. I work at home and I can't cope with the fact that most days when I leave my computer to go and see how he's doing - I'm going to find some ADD thing going on - definitely not what we discussed and agreed at breakfast... I'm exhausted and worn down by it...

I feel there's nothing more I can do - so I've decided to stop trying to find any solutions and just keep stating what's a problem for me - stop work on the house (our worst battleground) and leave it to him to work out what he wants to do - which I have to accept may mean leaving me. 

Is that the right thing to do? Has anyone else successfully overcome this barrier?