We have 4 kids and have also been losing our shit. I still have to work full time, so my wife has taken on "teaching duties". Today she realized this isnt just reviewing homework, she/we actually need to be the instructors. Homework reinforces things that at taught in school.... in the matter of a few days we're now into the "teaching at home" phase. Kids dont learn by watching a video or reading a paragraph, they learn by explanation (like when I explained in many ways what a "square foot" really is to my 8 year old today). They're no longer "doing homework", they've already reached the point of not knowing what the f@#$ they're supposed to do. Its not the teachers fault either, they didnt see this coming.
This is painful for all of us. I feel your pain. Deep breath and remember it's not the kids fault. They'll probably be telling "tales" to their grandchildren about these days.