Oh Fiona. i could have written that post myself hun, the exact same thing is going on in our house with Nick
I am still trying to figure it out, but i know that making a big joke out of it makes it worse for me, my dp does the same as your dh and the next day when dp is at work, Nick thinks he can do what he wants because if i put him in his room, shout, time out, whatever, daddy will come home and save the day and make me look like a complete idiot.
I'm sorry i have no advice, just i know how you feel