So sorry to read this and I do understand. It is now over ten years since I was in a similar situation and I'm trying to think back for anything useful to say.
I hope G managed to sleep and to feel a little more refreshed today. I remember a doctor telling Mike to think of energy as money in the bank and on a good day to use a little, but save some for tomorrow. But it is so important to do the things you want to do, see the people you want to see, so probably best to overdo it sometimes, and rest afterwards.
It is difficult to cope with the little things like resetting the oven clock - I've only just learned to do mine, I used to wait for my son to visit. Bringing the shopping in, clearing the drive after it snowed, are the things I remember sneaking around to do so as not to cause Mike to feel frustrated he could no longer do them.
On a positive Mike did start to rely on me in some respects and started to let me do things for him which he realised he couldn't do - I still feel it was a privilege to be able to do so, and it still brings me comfort to remember.
Spending time just being together, dealing with that day's problems and trying not to think about tomorrow helped, but it is so different for us all, please do what you instinctively feel is right for you both.
And take any offers of help, people want to help but don't always know what to do. It may make a big difference just to have someone nip to the shops for something you need. Or to sit with G whilst you just grab a breath of fresh air can make it easier to cope.
Try to take care of you, rest even if you can't sleep, eat even if you don't want to.