My mum hates my dad.

She stays with him because she wants to inherit his property in the case of divorce/she outlives him. She's said this many times in his absence, and constantly curses him and wishes for his death. I honestly don't understand why she married him.

When I was younger she'd constantly tell everyone about how he altered the written prescription on her flu medicine to try to poison her.

She behaves a lot more calmly now that she managed to find her old flame and cheat on my dad with him (she used to throw massive anger storms for hours and days on end, because she was obsessed with him but society didn't allow it). But when he retracts attention from her she starts shrieking at and verbally abusing my grandmother, citing that she must have told her lover something to make him hate her/not want to talk to her anymore.

Why are women such psychopaths? They don't deserve to be treated as human beings, the way they behave.