My nephew 4 yrs old has been with me for six months I have full legal and physical custody. My sister was supposed to "get her life " together in 1 yr so the boy could be with her . Six moths in, everything is still the same with her. The fathers a DBD. My nephew has recently choked the cat (cat died ). Tells my 4 yr old son that he's going to kill him. Will randomly hurt my son. I'm afraid for my son and the other animals in the house. I love him so much but I don't want him here anymore. I feel like putting him up for adoption is the only way. I've called every friend and family to try and find a spot. I don't know what to do

A 4 year old strangling a cat to death is considered serious. First contact Social Services. Second arrange for a Family Court date to change custody. Your sister (and the father) are the only ones who can put him up for adoption, unless he has been removed from all chances to be reunited with either bio parent.