OP, depression and mood swings are common symptoms of MS, so I'd factor that into how you react to what comes across as unreasonable behaviour from DH.
Every person with MS has a different experience of it - the level and type of disability varies so much. And even if it isn't so bad now, you can't predict how things will go in the future. There are some new drug treatments that have proven very effective so far, but they haven't been around long enough for there to be whole-of-life data.
So it's vital that people with MS take care of their mental, physical and emotional health, to give themselves the best chance of a satisfying and active life. If he has Relapsing-Remitting MS, the most common form, the idea is to reduce the number of relapses, because each relapse can leave you with a bit more disability than before.
It's a life-changing diagnosis for all three of you, especially as up til now you've been the one with health issues. DD now has two parents with long-term conditions.
You sound like a loving family - love that you're doing a x-stitch Lowry for him! - and he sounds like a good dad and husband. So don't let this upend you.
Maybe all have a calm discussion about what it might mean for you day-to-day. Dad might be more short-tempered, and have physical limitations eg extreme fatigue (which I'm sure you get too).I haven't read the other thread you mention, where you talk about MS, but check out https://mstrust.org.uk/ for support, advice and information on living with MS.
Long story short, both of you will need more help from DD - even if it just means looking after her room and doing her own chores (like the gumshield) a bit more.