Hi CC,
You have to learn to manage you time/hours. I get just so many real good hours when I want to get everything done, cooked, or cleaned. The list never goes away, like bills.

I try to make a list and do one major project a day. That's all I can do without hitting the wall, as you said. I can lots of little stuff done, then nap, and then carry on with normal stuff the rest of the day/night.

If I really overdo it, it takes a day or days to recoup. Time with the kids is very important.

Try to take some time from your day and put it aside for them. You are very important, but you are very important to them.