My husband and my son

My son has ADHD.  He has always been difficult.  He moves to fast, talks too much, can't maintain relationships.  People just don't like him.  He tries to pretend to be "normal" and can for a bit, but once someone gets to know him he can't maintain the "cover" anymore.  Once in therapy he was asked why he was so good in public, but so awful at home.  He said he could only hold "it" in so long and home was the one place where they have to love you so it is ok to be yourself and so that is where he let go and was just him.   It hit me hard.  I understood as with being depressed sometimes you can't hold it in anymore and have to let it out.  I like to do that when I am alone, but sometimes you can't wait or you just aren't going to be alone.  I have chosen to love my son.  He has many good qualities, gives great hugs, notices when I am sick or tired and no one else does, sometimes does things just to make me happy...However I don't think my husband loves him. 
He seems to resent him and just can't stand to be in the same room with him.  Honestly even his mother said he started most of the fights with my son.  She came to stay for a week once and did not like the way my husband treated my son.  She even told my parents so.  My husband asked once if him not treating our son right is what caused me not to love him anymore.  I told him yes, but it didn't change anything.
When my father died my mother came to stay and she told my brothers my son was horrible and she moved out saying it was his fault.  The funny thing was he knew how much my mother meant to me and he only had one outburst the entire time she lived with us.   The one outburst is what she used to move out, but she told my brothers he acted like that every day.  I asked if I had missed something and my husband and oldest son both said she was crazy as my middle son had been wonderful the whole time she was there.  I had a big fight with my mom and it seemed to scare my husband he suddenly started tolerating Zachary's obnoxious mouthiness.  He just shrugged it off like it didn't matter which is what I have done for years, because it really doesn't.  He doesn't mean most of what he blurts out.  No matter how hurtful it is. 
For 3 years things have been better, but in the last month they have gone back to "normal' with they yelling and snipping at each other the way they used to.  It is so much harder this time as my oldest son has moved out.  He was a cool head and would tell them to stop and both respected him and would listen.  It helped me so much as I did not have to get in the middle and chose anymore.  (My oldest son now resents me for that and I have lost his love and support, but I can not go back and change it now.)  I always felt I needed to stand up for my son and my husband just resented it so.  But my son was a child and a child with a disability.  How could I not stand up for him.  I always felt my husband was the adult and should be able to control his temper better than a child could.  My husband didn't see it that way.  He refused to put Zachary on medication, I had to, and I had to give it to him for years, my husband wouldnt', he refused to go to therapy with Zachary even when I begged, siting he was military and it might interfere with his security clearance...he refused to read books about ADHD...basically he did nothing, but accuse Zachary of disrespect as if Zachary was doing it all on purpose.
Now we are in the downward slide as my son is graduating and moving out in 6 months.  I have no idea why my husband suddenly is yelling and getting so angry at everything again.  He knows we are almost done.  It just drives me crazy he can't ignore the behavior just a little longer.  If he actually drives my son away so he won't come home and visit I will never forgive him.  My other two children barely know I exist, my middle son is the one who still hugs me and calls and texts me.  In spite of everything he is, I am going to really miss him.
Yesterday was bad.  My husband was off work and he and my middle son were arguing and yelling half the day.  I got in the middle of it twice and my husband always thinks I am betraying him when I don't turn and yell at our son. The arguments were stupid and just a result of Zachary's big mouth. Example.  I asked someone to tell me where to find a Fed Ex drop box  Son stops the game he is playing on his computer to google for me.  son tells where a FedEx drop box is, husband asks him to read the description of the place again.  Son refuses says he should have listened the first time.  Husband starts yelling "then I don't want you talking to me.. just stop talking to me.."   Son  "fine then I won't help you find it."  Husband shouting at son to shut up...I tell them both enough and to stop.  They both do, but husband is glaring excessively at me and I feel like dirt.
Later...I had baked bread and husband said he would wash dishes.  He washed bowled, but bread was still baking.  When I finished I started to wash the pans the bread baked in and son said Dad will be mad, he said he'd do it.  Son was right has happened before so I left them.  Husband cooked dinner, washed dinner dishes...I when I went in the kitchen all the bread dishes were in the sink still.  I looked at husband and said thougth you were going to wash them.  He said he was, but they weren't there when he washed the bowl...son comes in and starts in trying to tell husband they have been in the sink a long time, in a loud mouth, obnoxious way...husband starts yelling at son that he knows when the dishes were there and when they weren't and they weren't there....he slams his hand violently on the counter enough to make a really loud noise and rattle the items there.  I whirl on his and say "what is wrong, why are you acting like this?"  Son runs out of the room and gets on computer again.  Husband goes off about son being obnoxious.  I tell him yes he was, but over stupid stuff like how long a dish was in the sink, not a reason to get so irate.  I point out calmly to husband the dishes were in the sink when he cooked supper.  He admitted yes there were there the whole time.  That is what son meant.  Husband says well he was too busy cooking to wash them.  Then point at the pan in the drying rack that he had washed after supper and said he must have washed it right over the top of the bread pans.  He stared at it a second and admitted he had just washed that one pan and left the rest in the sink.  He walked over to the sink and washed them.  Son and husband proceeded to not speak to each other.  I went up to the bathroom and cried for a bit.
Just can't handle when husband acts this way.  Wish son would shut up and be "normal", but he never will.  Don't know why husband has to get so angry over such stupid stuff.  Wish he would yell at the youngest over forgetting homework and flunking tests, but he tells me I am too hard on that one.  Our ideas of what is important and deserve yelling are so different.  But I do know my middle son deserves loved by his family and I am the only one giving it.  It is so hard as sometimes the things he says and does hurt or anger me too, but I always have to hold it in and be the calm reasonable adult.  I wish everyone else would grow up too.