Unequivocally your DH is a behaving like a complete and utter absolute arsehole.
Am dram is a hobby, not a lifestyle choice FFS. The clue is in the name AMATEUR DRAMATICS.
His life, your life, the children's life and the welfare of the family don't depend on it!
It is a choice he is making.
Grown ups don't conduct a marriage like its a Noël Coward play, with flouncing, and huge sighs, disappear stage left, reappear stage right the following morning !?!
Tell your husband to get a grip, or piss off. Rude, inconsiderate, selfish, twattish, arsehole entitled behaviour, and in front of his family!!
Under no circumstance cook for his family to maintain the illusion of happy families, you are not. Your DH might like to go around pretending three nights a week, doesn't mean you have to live a pretend life!! WTAF?
Try really hard not to shout, I would be unable to contain my temper, as it gives DH an excuse to justify his behaviour.
Remain calm, "DH family, there will be no lunch today as I don't know where DH is or indeed where he has been so I can't possibly cater for you. I am sure you understand that I have work to do. Lunch is cancelled, please make your own arrangements." Then open books with a sigh, leaf through pages of books, sigh, stack and unstack books, wistfully, more sighs, perhaps a flounce, disappear stage left.
Best piece of MN advice I've ever read is applicable here, on Mothers Day.........tell your DH to
Fck off to the far side of fck and when you get there, f*uck off some more.
Contact a lawyer on Monday, see how he likes a real life drama. Twat.