Amom,
I encourage you to ask this question of the psychology professionals here on the MS site. They're extraordinarily knowledgeable. Otherwise, we will all give you conflicting suggestions, our opinions based on our own set of experiences and life filters.
Without a doubt, speak with a psychologist who specializes in the field. Perhaps it would be best to first meet with one on your own without your son. My guess is, a good therapist will help you address and manage the issue without compounding it with unnecessary and more traumatic drama.
_________________________
I have taken to the stand-up comedy stage to educate other male survivors and those who try to love them. I blog about my isolated religious upbringing where physical and sexual abuse were commonplace and I serve as a facilitator of a weekly support group for men who have suffered sexual assault.