How to discuss ADHD without spouse feeling blamed

My husband will not talk about his ADHD at all and seems to believe that taking medicine is the cure all. He is ashamed of his diagnoses, and I believe that prevents him from being able to even acknowledge how it affects his and our lives. It's been two years and after minimal adjustment of his meds, he thinks he is fine but really all it is doing is giving him more focus at work and tempering his moods somewhat. When he delays taking his meds there is a noticable darkening of his mood which improves upon taking his adderal and welbrutin, however he is still so mercurial that I get whiplash from his changing moods.  He has always had a very short fuse, but after a brief period when the medication greatly improved his demeanor and outlook, it seems like he is back to the same old Dr Jeckll/Mr Hyde. One minute the funny and loveable man with whom I fell in love and the next a volatile jerk who ignores me even more because he is so focused on work, tv and/or the internet. I am so unable to cope with this that I finally found a new therapist and am desperately trying to stay married but the grass on the other side is looking ever so much greener... 

There is never a good time to talk to him. If he is in a good mood, I don't want to capsize the boat, and if he is in a bad mood then I try to stay away. He started in on me for reading "self help books" and blaming his ADHD for what he clearly thinks is 100% my problem, and I eventually found myself screaming at him to read this book. Not my finest moment. He will not listen to my very rare and gentlest comments about how I'm not blaming him, it is his symptons which are controllable. I have read nearly every marriage book I could over the last 16 years, but now that I understand ADHD better, every lingering issue we have had makes perfect sense to me. I'm torn between feeling hopeful that we can be one of these success stories and have a happy marriage, instead of just happy moments, and feeling completely hopeless because I don't foresee him doing anything at all on his end.

He was diagnosed by his GP, and I have gone to him and discussed referring my husband to a psychiatrist. The trick is how to get him there without my husband knowing that I am behind it and becoming furious with me for going behind his back. He won't let me attend appointments with him and at this point doesn't even go see the doctor. He tells me when he is on his last pill or two and I have to deal with picking up and filling his Rx. The GP said he can tell him he needs to see him and will suggest referring him, but I know he will say everything is just fine, and he probably believes it is because shortly after every fight he asks me what's wrong with me. Completely surpised that I could be upset about anything, even if we had just finished discussing divorce.

I need to find the courage and a way to get through to him that I cannot live on this rollercoaster anymore. I still love him, but sometimes I think we'd be better off as friends and co-parents.