Book for Teenage Son??

I think it's useful to remember that when we teach a person what not to do, it's not enough to leave a void where the wrong behavior was. You must replace it. So, as much as focusing on the dangers of porn, you should focus on the ways to view, respect, and treat women in friendship, school/work, dating, and in relationships. More than saying "don't run on your own initiative," the coach should say "only run when you get the signal."

 

"The time is right" has been and gone several years ago. I say that because in the testimonies of the teens on this site, they were doing PMO years before they were 14. The right time is before this destructive, life-changing, brain damaging behaviour is started.

Well, to do some remedial work is all that is left to you. So, so not delay any further. You must speak openly and directly to him about this. Sharing your own disastrous decisions may well give him pause. Even though you and his mum are not together, surely you two can have a conversation about how to handle the crisis that has arisen. Here is a video you could watch together. It is rather late in his life, but this could kick-start your sex education of your son. I recommend it:-

 

If your son has a faith, this one may help him a lot:

 

This one deals with it scientifically. It is heavily detailed and might be best to watch it in two sittings...

 

Don't sugar coat it. Show him facts, show him what progressive addictions can potentially lead to (mentally, physically and legally-occasionally).
It's a very adult topic from a mature point of view, it's either something you talk about seriously as an eye opener or not at all.
Share your experiences (without explicity), but how it knocked your social confidence or perception of sex or whatever else may have been affected.
Dont force and ideology however, but provide the contrast, thus influencing conflicting thoughts which in turn will help him decide for himself hopefully.