My ex-husband and I have had shared parenting for six years, and everything has been very amicable. He now is trying to gain custody of his troubled 17-year-old nephew, who is in a halfway house, and have him live in the same house during his parenting time, with my young children (daughter, 11, son, 9). I do not want the nephew around my children. He has a history of violence and was a victim of sexual abuse in the past. What is my recourse?