Why does bloody mary kill you?

One time, a woman (Bloody Mary) lost her baby. She went out looking for her lost child, but never found it. So to this day, if you go inside your mirror and say: Bloody Mary,Bloody Mary,Bloody Mary, I killed your baby, I killed your baby, I killed your baby, she will kill you. Another reason why she kills is because one day she wasn't pretty and everybody laughed at her. She went home and she said this in front of her mirror: From this day on, whoever summons me and looks at my horrible face, I will stab them to death.

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This is folklore and is not true.