Yes I find my mum very difficult. It's her way or the high way. She gets an image in her head of how things must be, and sees her arse BIG TIME when things don't go that way. Christmas must go a certain way, birthday's, mothers day being the next one - she orchestrates the lot to suit her exactly. Even if it massively affects or puts out others (such as forcing my Dad to sit for a big meal, when he is terminally ill and can't fucking eat.. obviously he didn't sit through it, I told him to go back to bed and gave my mum an earful!)
She is a drama queen and kicks up a big stink about stuff, is hugely judgmental and nasty about people (oh she had a c section, too posh to push ha! then wonders why I struggled horribly after a crash section!!)
I still haven't quite forgiven her for the way she tired to force mine and DH's wedding into the mould she had in her head, which really ruined the excitement and planning, as it was constant loggerheads - to the point I told her to stick her financial contribution, as it doesn't give her a right to dictate the day.
When we had DC1 my DH ended up having to have words with her, because she was being a judgmental cow about things we wanted to do.
With the way we parent DC, she HATES if we do anything differently to how she did it.
The thing is, I would hazard a guess that she thinks she's the most wonderful, kind hearted person, a wonderful Mum etc. She wasn't bad by many people's experience - but I have a very different memory of my childhood and experience of her behaviour, than she has.
What truly baffles me is absolutely everyone thinks she is the most lovely, gentle, kind hearted person blah blah. She walked out of a family members wedding because she took offence at something the guests were doing FGS - the bride and groom were baffled. Yet she's still "lovely aunty sue!"
Anyway.... I'm glad I got that off my chest..!
In an attempt to answer your question - why is she like that... she has alluded in the past to her DF being very abusive - throwing plates at her DM. He also beat my GM up in front of my mum etc. She rarely talks about it, this is stuff that slipped out when her DF died, and I was shocked when she said "good riddance horrible man!" (which was not my experience of my granddad)
I think there is a lot more to that, and I also wonder if there is an experience of SA too in her past. She won't open up though, she point blank refuses any therapy - so I take her as she is and tend to keep her arms length.