I think my husband has undiagnosed adhd

Finding this has been an absolute God send and my brain is going crazy trying to get all the info i can!  I've been married for 22 yrs and have 4 children.  My 2nd born has been diagnosed with adhd and depression at 14yo.  My husband always said he has the attention span of a gnat and that he knows he's selfish but doesn't mean to be hurtful.  I've learned to not rely on things he says because he says 
"i changed my mind" all the time, and he often completely forgets.  He does what he wants to do, when he wants to do it, regardless of others most of the time.  I've learned to write him if we need to communicate about a deeper topic because he interrupts all the time and a simple topic turns into a fight with him just walking away.  We are both extremely stubborn so it doesn't end well.  I always thought I as the problem, high maintenance, demanding, expecting too much etc.  Now i can see that I'm not the big problem.  Obviously I've got things to work on, just meaning that I'm not as bad as maybe I thought I was.  Make sense?   His highs are so high, and revolve around exciting and new circumstances, his lows are low and revolve around difficult circumstances.  He wants to move every 5 yrs to seek new adventure because current situation has become boring and well, not new.  Always wants to be on the go and bored, seeking new things to do and I'm a home body just wanting quiet and stability.  He makes impulsive decisions but doesn't always act upon them.  For instance, we had a life change recently and we said we'd always keep our current house as a "home base" no matter what happens.  I should have known better trusting him.  Just this wk end he came home and told me we are selling the house.  

He can hyper focus like it's his job though!  And he often asks like a child with my kids who are older now and thinks it's stupid, where once it was awesome to hang out with dad.  Even my 11 yo looks at him weird.  How do I wrap up 22yrs worth of experiences and life into one message to show that everything has become so clear and I just keep going "Ohhhhhhhh, that makes sense now!!!" 

I'm so lost at the moment with what to do with all this new info and where to go from here.  He thinks add/adhd is not a thing and stupid.  I agree it's a blanket diagnosis often used too much in young kids in school.  But this seems legit and he fits so much of it.  I want to talk to him about it but, well, there's the listening thing, the thing where he jumps to conclusions and discounts me, and the thing where he thinks this really isn't a thing!  I'm not trying to change him, but rather for him to acknowledge that this might be a factor in our marriage that has caused much harm.  Even getting treatment imo isn't as high a priority, but to just know that this is part of it.  kwim? 

Guess I'd love to know how you approached it with your spouse who didn't really think it was legitimate?  I'm a but nervous and look forward to hearing from you!