There was a mum at my primary school, i.e. when I was a child, who was a bit like this but worse. How she got away with it all I have no idea, but her behaviour was out and out, over the top, scary mental.
I liked her daughter, her daughter liked me and for ages her mentalism had no impact on me at all but did on another friend's family and it was pretty horrific. Then my father died and for some reason she used this against my little brother and me, but mostly me. This was in the seventies, so excuse "really bad parenting leaving your child alone, the horror!" My mum needed to make more money after being widowed, so for two hours a day, but not every day, she was a barmaid in a pub, five minutes from our home. I could call her there if something was wrong at home and she would come straight home. I think I must have been a very mature ten year old although I became a very emotionally immature teenager/adult, so who knows! So her "game" to play was to call us when she knew my mother was working and breathe heavily down the phone and say "Raven, it's your daddy, I'm dying, I need water."
Some people are just fucking bad to the core. I don't know if she was normal before she had children, but she was certainly a monster when she did have them. The situation got sorted, the police were involved, but she then went on to harassing my "aunt" - actually my mum's cousin - who lived a couple of doors down from her.
Break all contact with her, tell the school about her stupid behaviour and look forward to your daughter being at a different school next year. The daughter of the monster and I went to different schools and that was the last we knew of what the mentalist was up to.