Is this the right path

I am my 7 year olds son custodial parent. I had my sons dad James slapped with a random drug test in Jan 2016 because of the way he was acting . He failed the test and his parental rights have been suspended . In May of 2016 he was arrested for raping his 11 year old step daughter, child pornographic pics and videos and some other horrible things . He was supposed to go to trial in Feb but now James is saying he is crazy and not responsible for what he does when he blacks out. My son is autistic and has alot of problems communicating. Since James has been gone his grades are amazing. He has stopped having nightmares . He has stopped having episodes at school where he cries for hours wanting his mommy. And it all stopped when James left. I have obtained a lawyer. I want sole custody of my son. My husband and I have been together for 4 years want to adopt jt. And my lawyer says James has to hurt my son for him to lose his rights . Is that correct? just needing opionions