This probably sounds a little silly and a bit extreme, but what about going on strike, ww?

I'm completely serious. Stop doing anything for your kids. Heck, I'd post a sign on the door to your room too. 'Mom on Strike' Fix dinner just for you. Do just your dishes. Wash just your clothes. etc.

May serve as a wake-up call. May not work at all. But its something to try. Let them realize just how much you do for them. For a while, take care of yourself first.

That's ok, Moms are people too. They have needs. As a kid (even as an adult kid) its easy to forget that Mom needs stuff too. I've been guilty of it myself.

All kids can be selfish, especially if they have a good mom taking care of them, but at some point, they need to appreciate your time and effort instead of expecting to be taken care of.