snapyap
re your comment:-
"His parents seem fine and happy together to me. MIL gets her way and calls all the shots. DH says pils used to be violent to one another and planned to divorce when bil hit 18 but that hasn't happened. They're all devoutly religious and hide their shortcomings behind that.
Is this relevant? I don't even know".
It is relevant, we after all learn about relationships first and foremost from our parents. His parents are patently not happy and hide their dysfunction behind religion. What his parents taught him is a shedload of damaging lessons. My guess is that he is most unhappy about his position of being Number One in his household usurped by his son because you are now his parent (rather than simply running around doing your Hs bidding).
He may be tired but its no excuse or justification and besides which you likely are as well, its not a competition I would put a fiver on it that he is only stroppy to you and in turn your child. To everyone else including his work colleagues, he is Mr Wonderful.
What did you learn about relationships when growing up?
What do you get out of this relationship now?
Some abusive people do appear to be plausible or otherwise lovely to those in the outside world and that includes family. They do not have to live with him every day as you have done.
Your mother's so called counsel is not just wrong on so many levels, its damaging as well.
My guess too is that you will find it too hard to call him directly on it next time he sulks or strops, this is because you are also afraid of his reaction if you do so.