My heart goes out to all of you. I used to work fullt-time/part-time as well. Even though it was tough at times, I was much happier with the situation, especially knowing where my boys were. They were young at the time and being home all day was no biggie, but as they got older I started to worry about them not being able to go anywhere during the days I worked (my daycare provider chose not to drive them around, what can you do??). Luckily, I was able to quit and am available for them All.Day.Long. 
It can be done. I didn’t think it could be as I was very new to homeschooling, but, now with the experience of hsing under my belt, if I had to go back to work I would know it is possible. It just takes some extreme planning (I probably planned better then than I do now!) and people being on the same page, or there about.
This is a hard place to be, but with audio books, educational material online/tv, good books, outdoor time, sketch books, someone to narrate to, read poetry to, do math drills with, etc., it can be done. I know it’s hard, I’ve been there, so please don’t think I think that it’s easy-peasy, but I had to learn that homeschooling does not have, nor should it, replicate ps…I was trying to make it look like that in the early days and that just made it harder on my dc and daycare provider.
Best wishes to your friends. Please let them know that they are not alone.