How do I help my in-laws understand my husbands ADD?

HI Everyone. This site has been a marraige saver for my husband and I. We been together 12 years, married almost 7. Last month we seperated for 2 weeks, niether of us could deal with the other any longer. A bit of hitstory... After years of not feeling loved etc (typical non-add spouse feelings) I had an affair. I deeply regret it, especially once my husband was diagnoaed with ADD. To find out he really wasn't the jerk I thought I had married and that i had done that to him...the guilt is amazing.  Anyway, during our two week seperation he went to his parents for support. They know about the affair, but refuse to believe that ADD is a real thing. While a contributing factor in my affair, it was not the cause, I know that I was. He wants them to understand what has been occuring in our marrige, perhaps to shed light on my reasons for stepping out. They just wont hear him. His father (who has to also be ADD) says it's just the doctor wanting him to come back every week to get paid etc. Very old school mental health thinking, it's all a crock. But it's ruining my husbands relationship with them. And they dont see this. He's sent them this website to read through, and says do not contact me until you've read this and done some reasearch on add. They refuse. They say I"m so controlling (his words while we were seperated when he hated me, he understands that his feeling that I'm controllling is part of his add) that I've brainwashed him into staying with me. He's caving, and making a terrible mistake they say. But they forget, that they would have lost their son 12 years ago if not for me. Not only is he their only ADD kid, but he's also the middle child, so he always felt and feels as if he's tossed aside for the older golden boy and younger baby sister. His father even agreed with this once that he was. My husband has had it with the additudes, not only towards him, but towards his add. He's not going to communicate with them until they research, but he knows that they wont, they're too proud. He's said we have to move on with our life without them, he loves me and our little family (2 dogs that are our kids) and that's all he needs, b/c that is all he's ever really felt that he's had.

 Should I try to get involved? It breaks my heart that in his hour of need they do this to him. He went to them for support and all their doing is yelling at him. Shouldn't it matter to them what he wants? Shouldn't it matter to them that they loved me like a daughter and on numourous occasions thanked me for bringing their son back to them? Yes I made a terrible mistake, if my husband can forgive me why can't they? especially knowing if they don't they'll loose there son. Which is his decision, not mine. Why do they refuse his add?


Thank you ! Jess