Was in similar situation for roughly ~4 months, what helped most is fixing my sleep (up to 7-8+ hours every night; this takes a bit of education and then some discipline), some quick(~10min) yoga nidra daily (it’s very simple, nothing to learn - this also refreshes & compensates for some missong sleep) and 4-8000 units of vitamin D.
PS and of course pacing: learning what triggers “bad days” and in general moderating your mental/physical activity = split everything you do in smaller parts, at least halves, this includes meals[!] and even just googling/shitposting.
We learn and overcome in time, the real trouble is another incoming infection, and then another one…and all the folks laughing at me being the only one with mask on my job, or anywhere in fact.
PS Speaking of your partner’s diabetes, Mike Greger (Nutritionfacts) has some tips; it is possibly 100% reversible!? Anyway I’m not expert - check this https://nutritionfacts.org/?s=diabetes
PPS