Ok, I've got away lightly too by the sound of it, as MIL is just annoying rather than psychotically evil.
Main problem is control freakery. No matter what she's doing, she manages to 'ask for help'. Somebody needs to taste her cooking for her
, fetch her paper, show her how to record a programme on TV - and it doesn't matter what you're doing, she'll screech at you until you come and help.
Sits on her arse most of the day, watching soaps at full volume and goes on and on about any sort of helps she does and how tired it's made her (she sometimes cooks the tea).
Brings conversations to an end because she's always done everything better, younger or more dramatically than anyone else.
Rang me up the day my Mum died to tell me how much she'd miss her, how upset she was and what good friends they'd been (I can imagine my Mum chuckling in her grave at that one).