"Healing the Child Within" is a good book; as well as "The Wounded Heart"...
"Healing for Damaged Emotions" by David Seamans is also good, depending if faith is part of the value based environment or not.

I think if the boy is open, definitely a good counselor/maybe female? depending on who abused? but someone who is not family an "neutral" can provide a sense of safety and provide an environment of healing...