nephew's mom abusive

[evva]

My nephew is 9 years old and already shows signs of behavioral issues. My brother and his ex-wife are unfit parents. How can we go about taking custody. CPS has reccommended that my parents get temp. custody. My brother is not abusive but not around due to his drug addiction. The child's mother is abusive to everyone including my nephew. I seriously believe she is mentally ill and has an extensive background that can prove her violent. Please help, we are fed up with her abuse, threats, and harrassment.