Upcoming assessment nerves

We have finally booked the assessment.   My wife talked to the guy who will be doing it, and he seems very nice.  Having heard from a few other people this is an extremely difficult meeting.  I am on the fence as to wether it will just be Dad & I or, all 3 of us.  Part of me wants her there for my own sake.  However he seems to open up more when I'm the only one around.  I'm still thinking it over. 

To a degree she has become the "bad guy".  Which is problematic.  She is the one that tells him to have a shower, change his underwear daily, etc.  There have been a few random arguments.  Just the other day he had made himself a fried egg sandwhich and then promptly washed the smoking hot frying pan.  Which warps it.  It's already super warped, so it's not going to get any worse. 

I was sitting on the deck and overheard the conversation.  (mild argument).  This ended up with him going for a walk, and then going straight to bed.  This left me in a terrible mood.  Part of the reason is I know both sides of the story.  He's basically reverting to a child, and she is worried about her things.  Telling him multiple times will not solve anything as he won't remember.  I spend most of my time making sure there is peace in the house.  

I am not allowed to have a bad day, or be off.  I have put this on myself.  When I get to the point that I can't handle it anymore, I just nap.  It's the easiest thing to do.

Unfortunately you really need to just place your own needs, mental health aside until things get figured out.   I understand that you can't really care if your glass is half full (or whatever that metaphor is).  I'm doing my best. 

I know I need to break it to him about the assessment.  This has been on my mind for months.  Part of me thinks I tell him the day before and the day of because he won't remember at all.  Part of me thinks I need to break it to him gently over the course of the next week.  It will likely be between the two things. 

I have no actual time for myself really.  A long time ago, we made an agreement to not have kids, be selfish and create our own life.  We are not in anyway prepared to deal with this.  Every day, week gets harder.  I used to enjoy playing music, and D&D.  That's kinda gone out the window.  Every waking moment I have is trying to navigate this situation.  I'm either thinking about things I need to do, doing the things, keeping the peace, etc.  

I'm worried about myself to be honest.  I keep thinking "I'll relax when this or that happens".