Violence of a Mentally Unstable Person

A mentally unstable person lives in our house(my matrimonal house) since the death of her parents,my husband's aunt. She becomes violent whenever she doesn't get her way. All her problems are with my in-laws but because she is afraid of them(they scold/slap her when she becomes violent to control her), she makes me her target and throws things at me. Today while my mother in law was scolding her, she pulled my hair and beat me with shoes. After that she tried to drink phenol and threated that she would write my name in her suicide note. Once before, she had hurt my daughter's hand. She threatens us that she would go to the police and logde a complaint of violence against me. I don't know whether I should go to the police or not. Some people adviced me not to go to the police because human rights would support her.