Protecting the kids or letting them see what is real?

Long time lurker here, posted a couple of times. My backstory: my 9 year old son was diagnosed with cancer at 8 months old and he fnished his loooong treatment plan and fully done and released in Sept 22. So we are almost fully out OUT which is a big deal. And my husband has been recently diagnosed with ADD this year and is kinda doing ok, but kinda not. It's a roller coaster to be honest and one that I'm not sure I want to be on anymore (but that's for another post). I'm the non-ADHD spouse and will raise my hand that I've enabled, parented and all the other things that I've learned are not that great to do. My husband and I together for around 19 years, married for 15. My child has been displaying some tendencies at times, but nothing flagged yet for a diagnosis or anything yet. 

My question is this: how much do we 'shield' our kids from our spouses? 

I've noticed lately that my son has taken to requesting to make requests. My husbands under-management of his ADHD symptoms as well as his outbursts and definite disregulation absolutely RULES our house. I don't even know where to begin to try to correct it and it's so overwhelming day in and day out with how much has just been 'left' for someone to pick up and deal with (and I'm admittingt hat it's usually me who picks it up so many times I've been trying to work on NOT picking up the emotional baggage that my husband brings to each day). So my 9 year son makes these requests JUST TO MAKE A REQUEST. So he's literally asking to speak and ask a question before actually asking and speaking that question. It broke my heart yesterday bc I don't even blame him but I hate that he's learned this behaviour from me, our home, our family, etc. We often don't know what kind of mood my husband will be in and simple requests, i.e. picking up something, cleaning up after yourself, etc can be met with such anger and then some days he acts like he's shocked that we are walking on eggshells around him. 

But I am just so mad at myself for letting it get this bad. I don't even know where to begin to help correct it or even just help my son to be more assertive (if that's even the right word to use in this situation). My husband then will say something so off the wall to me about our son and then he won't even acknowledge that he was the cause of the distress and then doesn't do anything to repair with our son, and just ignores it and keeps going (and then wonders why our son gravitates towards me more).

Or maybe it's the case that it's best to just keep focusing on myself, showing up for my son and trying the best I can do...and leaving my husband to just flap about. It sounds cruel but I have depleated all compassion and empathetic resources for him. For me, in 10+ years I want to look back and be proud of how I acted and what I did. No matter the outcome. 

It's just so fucking hard. All of it. Exhausting and hard. Any advice in relation to kids - specifically when they are around this age of 8-10 years old. I'd appreciate it.