Agree with others, def chill with the 8hrs per day. Try to get 4-5 hours in of decent focus and you'll probably get more done than most people does in a day in a busy office. In these times though, just do what you can. Don't take the piss, but be reasonable with yourself and don't over-do it. Don't treat it as a temporary thing where you dig in and then return to normal after a week or two, plan long term.
Also, if you can, make sure you work in a different room and keep it as quiet as possible. Alternatively headphones on and volume up.
I did 6 months with my partner where we worked 6hr days (me 06-12, her 13-19) while the other one looked after our child. It was fucking hard and worn us out big time, so don't aim to get 6hrs in, I think 4 or possibly 5 is far more sensible.
Stay strong and vent here as much as you can, you're not on your own in this.