I would sit the boys down and explain what it's like to be the parent in charge and what it's like to have the mental burden of scheduling appointments, managing pick-up/drop-off, thinking about meals and laundry and clean-up all the time, for three people. That you are the real parent right now, and that all you want is a little respect of your time and effort.
They're going to hear this like the "adults talking" sound in Charlie Brown. Mwa-mwa-mwa-mwa. In one ear and out the other.
Relax. No need for lectures. Trust me, your kids will notice who does everything. Hectoring them about "I do everything, your dad does nothing!" just makes you the bad guy.