Threats from daughter in law for filing false case , suicide attempt..

Good day, I am staying in the same building as my in laws, but in a different flat. My in laws stay with their son and daughter in law. I have been noticing since quite some time that my parents in law are being tortured by their daughter in law which includes threats of suicide & filing case of dowry and attempt of rape against the father in law. Yesterday the daughter in law created scene by making cuts on her forearm with a knife. And this isn't the first time she did that. I didn't want to get involved, but I am now because now she has started threatening my wife (her sister in law). I am afraid it won't be late untill I will also be accused. I need legal advice on how to safeguard my family & myself & parents in law..