I would tell them. From past posts, your kids sound like respectful, good kids who love their mum so if they know you're struggling, they'll hopefully do the right thing by you. I think its also important for our kids to learn that things come along for parents too that are difficult to deal with.

I've told my girls lately (and they're substantially younger than yours I know) that I'm struggling physically and I need them to be extra good for me, tidy up without nagging, play well together etc. They've had times of playing on it when they know I can't get to them quickly enough or TBH just let it slide if its not dangerous, but most of the time they've been really good.

I hope things improve for you very soon.