Having to be responsible 24/7, to always be there emotionally and financially for our kids is very hard. Add depression to such stress and it sure can be exhausting. Mine have been out of the house for several years now, but I remember the times I just wanted to stay in bed and shut everything out. Or just feeling so tired, bleary-eyed, and cranky, but having to do what I had to do.
I would say to take some time out for yourself, do something you enjoy or go someplace, but I know in depression that advice often just doesn't work.

But I do think the idea Chocmouse had of letting your daughter go to your sister's a couple times a week or so is a good one.
Hoping you feel better soon.