A childhood belief about ghosts

I used to believe this about bloody mary,

bloody marry was a 18th or 19th century woman who lived with her husband and 2 children. Then, one day, someone came and killed her husband, and 2 children. She was upset about her husband and 1 child, but she especially loved her baby. She eventually went crazy looking for the culprit, and she died, now if you stood in front of a mirror in a pitch black room and chanted, bloody mary i killed your baby, she will come out of the mirror with a knife and stab you to death. My brother is 15 years older than me, and he always got a kick out of teasing me. One day, he took me into his room at night in the basement and told me that bloody mary lived in his mirror and if I was in here by myself, she would kill me. I didn't go to his room for another 2 years! yeah, I was like 7.....