Dear Beveryly,
I feel for you I really do. In 2010 my significant other had a C6/C7 complete injury. We're in our late 40s.
When you said "We argue about everything, everything!" I could easily relate because that's been our story lately. But we go through this from time to time. Then we have a big, raw, honest all out argument and get everything out on the table. And by everything I mean everything. Because if we don't, whatever we don't talk about festers.
Then we make changes where we need to. And there are no rules to the changes we make. If it works for us it works. We are very "out of the box" thinking kind of people and some solutions are unique one-of-a-kind things just for us that we came up with on our own.
So far this isn't so much a matter of what works or a plan (just like, as you know, nobody plans an injury like this) but it's what happens with us and we're still together. We also want to stay together (so far) because we both truly like each other's personalities. -- Do you like your husband's personality? Has your husband's personality permanently changed? Has yours?
I refuse to treat her as if she has a mental disability. In other words if I have something to say I say it. I don't go easy on her. But I also stick to the facts and no name calling. Just like she doesn't go easy on me. That would be insulting to both of us if either one of us did that.
Last night, I said I was "done". Then, around 2:30 in the morning we started to get to the bottom of things and today got things worked out - this time. I don't know what will happen next time, and there will be a next time, but if past history is any indication then I think this will be our pattern. But then again maybe it won't. Everyone is different, every injury is different, every recovery is different and every relationship is different. As you know, people and relationships change. Sometimes they change in the same direction and sometimes they don't. That's life! No guilt, that's just life.
For us, before the accident and since the accident communication's the most important thing in our relationship. The good, the bad, the ugly. I tell her when people hit on me she tells me when people hit on her. And yes, she's been hit on after her injury by both disabled and able-bodied men. Nothing is off limits for us to talk about. We talk about everything and sometimes we argue about everything but I think that's good to do. So far the talking is outweighing the arguing.
I didn't read where you mention having a "come to Jesus" meeting (big argument) with your husband. Maybe it would help if you did this if you haven't already. Maybe it'll help maybe it won't. What's important is for both of you to get everything out in the open. Be completely honest with each other, listen to each other, and then be completely honest with yourselves about what the other person's saying.
As far as his son goes. I'd just tell the son . . . look, you wanna come here? then it's gonna be like this . . . take it or leave it. Then you tell the son exactly what's expected of him.
The son's a know-it-all? Sounds like my sweetheart's mother. It doesn't matter what the son knows. What matters is what his dad and you need. And only the two of you can tell the son what those needs are. The son can't tell you what you need. If the son listens - great! If he doesn't listen - I'd say tell him to leave and stay gone until further notice.
It also sounds like the son needs to have it explained to him in no uncertain terms that his dad has had a very serious injury and with the injury comes bedsores and bedsores can lead to infection and infection can and sometimes does lead to death. If the son doesn't get this then he needs to stay away until further notice. Like the U.S. Marines' saying "lead, follow, or get out of the way". You and your husband lead - the son needs to follow or get out of the way.
Just thought I'd chip in with some of our experience. Hope it helps!