Advice on the hostile attitude of cousin's bride towards my mother

I am aged 34, stay in an apartment with my parents, wife and brother (5 members). My paternal aunt’s family consisting her husband, son, daughter in law and a kid granddaughter (age 3 yrs.) also stay in the same building (5 members). My paternal aunt’s is a very respectable family. The problem is with her daughter in law. She came from below class family in comparison, is a psycho path, hostile in attitude and suffer in inferiority complex. She (the daughter in law) becomes very angry sometimes, looses control, quarrel badly often with my aunt, husband sometimes and blackmails of committing suicide. She involves my mother sometimes and tells her bad words. As per the rules, the court is soft to the bride side so we hesitate to do anything, what are the latest rules, anything changed? Now in this situation what should I do to be secure my family and my aunt’s family before anything worse happens. Should I need to submit anything to the court or police station? Please advice.