Through the years I've analyzed her in absentia (she won't talk to me, and I gladly reciprocate). Her dad died when she was just entering her teens. She was the apple of her daddy's eye, and his death left her in the custody of her crazy inbred hillbilly mother and her older unkind brothers. She was sexually abused within a year of her dad's death, and soon fled north to join her older married sister who did provide her with some sanctuary. But sanctuary doesn't prevent a person from making a whole bunch of brand-new bad decisions, and she did. Instead of seeking knowledge and wisdom, she decided she "knew it all" and sought good times and parties and such.
That led to an unwanted pregnancy (Hi there!) and a lousy marriage, yoked to an undisciplined man who felt trapped and directionless. His favorite excuse was that everybody always lied to him.
On the surface it sounds as though you may be judging her a tad harshly.
Another born in here.
It seems to me that people become witnesses for several reasons.
one, to replace a family environment that they are missing. Maybe they've been abused or suffered some form of neglect and the witnesses come along with their love bombing and voila. Instant family.
two, they've suffered a recent traumatic life event of some sort and are vulnerable and looking for answers. Any answers.
three, they like to be a big fish in a small pond. Joe the window cleaner never gets to boss anyone about at work, but at the meetings he can walk tall and be admired.
There may be more, but they don't have to be an idiot. Not necessarily.