You just have to to do the best you can. If you are spendng part of your time "keeping the home fires burning" at whatever level that means, you are doing your best. When my husband was in treatment 100 miles away, I was over there as much as possible - then home to take care of "home stuff" and try to earn enough money to pay for all the bills. As caregivers, we just have to do as much as we can on every front (okay, so it's a war!) and somehow be okay with our efforts.
I made a promise to my husband when I had to break the "cancer" news to him after his first biopsy that I would be with him every step of the way - much like your post. I feel that I made good on that promise but, at times, the promise was realized by doing all the things that needed to be done in all the other aspects of our lives.
This is new territory. Your good instincts will see you through.
Best,
Anita