It does sound like Narcissistic Personality Disorder (NPD) (likely comorbid with histrionic, as you suggest). I grew up with a mother like that, and it did a lot of damage to me. Yes, they probably were damaged as children, and you can feel compassion for the children they were. But, as adults, unless they are self-aware and in therapy (rare) they won’t hesitate to hurt you if they feel they can get something out of it. I would recommend keeping far away. It’s almost impossible to get through to them, because any suggestion that they are doing anything wrong would be likely to cause them a narcissistic injury, and they will turn it back on you and make you out to be a terrible person.

An NPD mother is happy to turn her children against one another, even as adults, in order to get the narcissistic supply from some of her children sympathising with her over the “bad behaviour” that she paints the scapegoat with.

If a mother is prepared to go that far for narcissistic supply, imagine what someone could do to “friends” and/or lovers?!