I must admit like your sister I moved countries to escape a mother very similar to yours.
Very immature in her emotional responses, reacting to any attempt to make my own decisions with rage, verbal abuse or hysterical crying fits. She never lifted a finger to prevent my father from being physically and verbally abusive towards me either (instead use her usual hysterics to divert the attention to herself and make me feel guilty...). Used lies/manipulation to control.
I never saw her make a single friend, work or display any interests beyond shopping, watching TV and gardening . Pretty miserable and depressed all her life and always reluctant to have anyone in the house. Looking back now I also think she also regularly made things up/stories about the neighbours and loved to criticise everyone including her own sisters.
I was really embarrassed to go out anywhere with her as a child/teenager because of the things she did and said which were just, well, odd.
It is likely that there were some mental health issues or a personality disorder but she never showed any self-awareness or made any attempt to address her behaviour, and a she was living with an equally emotionally disturbed man so there was no hope that he would do anything either, it just was not a healthy environment. Various GPs kept pointing out to her that she had mental health issues/depression and should be taking medication or seeking counselling but she never followed through.
It was really exhausting as well because she was never happy in herself but expected everyone else to make her happy and fill whatever hole she had inside.
As people have suggested it is not your job to diagnose or fix your mother. All you can do is learn to minimise the effect she has on you and your life.
I just could not have her in my life and I only saw her sporadically once I became an adult and cut all contacts a few years ago. That might be an extreme choice but I had no real affection for her and I had to protect my mental and physical health at that stage.