What to do about the kid

Props to you for at least warning your lad about porn. That's more than most of us got!
I wish someone had told me all this stuff back then but of course we had no idea how addictive or detrimental it really was at that time. It's ten times worse for kids today because of smartphones.
Going cold turkey is really tough. I would say a guaranteed way to "fail" in fact so maybe as you phase yourself out of PMO gradually, do it in a locked room if possible...?

 

When you're ready to quit, you will. Hopefully it's before you're found out by your spouse or child or before much more time goes by. All I can say is that I wasted a lot of time with PMO that diverted my energy and attention from what's really important in life and I rationalized that is wasn't harming anyone, which wasn't true. And I can't get that time back.

 

I was watching porn on the web when I was 13.... and that was over 20 years ago! I read somewhere that the average age of first exposure is now 10.
I know more age varification checks have been put in place recently but the fact is, any kid who has access to a smartphone or PC can potentially view pornographic material. Parental filters help but none of them are perfect. Kids share stuff/show each other all kinds of material. Not just porn, all kinds of really grim/graphic stuff.
Education is definitely the key. Trying to censor everything just doesn't work. The more taboo you make a topic, the more tempting it becomes and kids being kids, they will go to increasingly elaborate lengths to find ways around restrictions. I think if you have an open dialogue with your family on the topic then thats a good start, and better than most.
Making kids aware of the potential harms gives them a sporting chance of making empowered and informed choices an not getting sucked down the rabbit hole like most of us 30+ guys did.