Hey OP
I've not read your other post, so you may have already mentioned this but where is your father in all of this?
Is he still alive?
How was he with her? What type of husband was he?
I can relate to a lot of the things you are saying but it's with my MIL. I've kept my mouth shut and just observed her behaviour for the last five years. Prior to that anything anyone ever did was not good enough.
Examples such as, family party and everyone turns up but she focuses on the fact that everyone has to leave. Pay for a meal at a super expensive posh restaurant or a super cheap place that she loves, eurgh food was okay, company wasn't great, oh and everyone had to leave at some point.
Christmas, expects extravagant present, gets extravagant present, not good enough.
Everyonr has to phone her everyday and talk for two hours. If not then she is displeased.
Silent treatment when she didn't get her way. One word answers.
Wants to see grandchildren, arrange it all on her own terms. If life gets in the way and you have to cancel then... well you get the picture.
Basically, her way or the highway.
I became like her. Then I realised. Then I stopped it.
My MIL is a bit of a people pleaser. She's insecure too. That's where the people pleaser part comes from. She people pleases for a boost and to make herself feel good. (I was the same).
She thought the world of her father and always tried to please him. She was his baby girl. He died. She was devastated.
Her husband is a lot like her son (my DH). They both don't give in ways which a me and her need in the relationship.
The lack of love and connection in her relationship with her husband resulted in her expected it or looking for it or burdening it to her kids.her sons and then the daughter in laws to follow and the grandkids.
My FIL isn't abusive or mean. He's just a bit useless and fails to love her in the way she wants (probably the way her father loved her, and I don't mean incest, just the amount of attention).
So when she burdened her kids with it or tried to replace her love expectation from FIL to kids, it was fine to begin with because they were kids. But then they grew up and flew the nest. They found girlfriends and wives and had children. Over many years that love began slipping through her fingers. Of course she blamed the daughter in laws because that was her logical explanation. 'You gave me attention and saw me everyday and loved me, then you met that girl and stopped visiting and calling so often... it's her fault'. As you can see that doesn't bode well for the relationship between son and mother or son and girlfriend.
What she was missing was, the lack of love from husband was replaced by children but children grow up and move on and have to live their own lives.
That didn't go down too well but she must have understood because shortly after followed the, 'I'm ill and I feel like I'm having a heart attack' stories or the 'someone died the other day, it could be me, would you be happy if I died?' - so the sympathy stories using her potential death as a guilt trip. The reporting of family illnesses and then making it all about her and how she feels and how it's impacted her. She's perfectly healthy.
My DH is pretty ill and has had an underlying health condition which means almost every evenings and weekends, I have the kids, I don't have the emotional support or just that 'how was your day' conversation. No laughs, no jokes, nothing. Just a 'hi how are you?', 'I don't feel great, please can you leave me to it?'.
He brings the money in and provides for us. But I need love. Love my parents weren't able to give to me and now my DH just can't give me what I need. I was about to turn to my kids for it but then I began saying things that my MIL would say. DH would take me out and I wouldn't be happy because he would have to leave after two hours. We went on holiday, I wasn't satisfied with the service etc
This lasted for about six months and I began sounding like her and I really despised it.
Had a good think about the why's and how's and what I felt. Lots of conversations with DH . Spoke to a therapist . Then figured it out. The lack of love in her life is the way she is.
The lack of love in my life in the way I need it and am pining for is the reason why I became that person too.
We've put changes in place to stop it. He's really good and so am I and our DCs won't go through what he went through or his siblings.
I mean maybe you can't relate but that's what I found. Helping me to realise her behaviour helped me to prevent myself from doing the same. Which also prevents DH and his siblings from getting upset with her attitude and it's how I've been able to let go of all the mean things said when I was blamed for DH moving out of the nest and living his own life with me.
Now we just ignore and smile.
I'm so sorry you're all going through this.