Only just spotted this:
"MIL aid of the generation he works hard so wifey should do all domestic chores "
you and DH need to form a united front about tackling this.
I am only just grasping the subtext about her policing your housework (not allowed to sit down, "what are you doing now" etc).
OK this is massively stressful. First you have to sort your own head out. You've internalised housewife guilt. Kill it.
then you have to get with DH and form strategies about how not only how he steps up, but how he visibly fully supports you in a more modern division of labour.
He might be sneaking off to do DIY, not only because it is easier, and he is being lazy; but also to preserve his status in his mother's eyes.
Nip that shit in the bud.
Book a time with your DH and have all this out. Set it up like a meeting - in the calendar, kids out or in bed - and have this conversation properly.
He might get angry. He might be a dick. then you'll know what you're dealing with.