Hi Matt. Good post and good topic. I'm not 100% sure what the correct answers to your problem are but I think you've already gotten some pretty good advise.
It makes me happy that he is married to a troll hag of woman.
1) To know that he's not abusing others. Do teen perps stop in adulthood?
Not usually. I suppose there are exceptions to every rule but, in general, most people who molest children do not stop with one victim and generally do not stop until they are caught. I know there is some statistic I've heard before that the average child molester will molest about 300 children is his lifetime. While I believe that statistic to be greatly sensationalized and embellished upon by the media, I do believe that most child molesters have multiple victims and normally do start abusing as teenagers.
The fact that it sounds like this dude has regular accesses to children is what really concerns me. Bill was right when he stated that it is up to the adults who know your abuser to protect the children in the community from him but unfortunately that does not always happen. Especially if they all think he's one swell guy which is also very often the case.
I certainly wouldn't completely rule out confronting him in private or sending him a letter. If you were to let him know that you remember what he did to you and stick it in his face, it would probably scare the hell out of him and make him feel he is unsafe. I would even suggest secretly recording such a confrontation and seeing if you can get him to admit on tape that he did it but that also may be illegal. I do know that the police in some cases have used that method to ensnare a molester.
Whatever it is you decide to do about confronting him or not, I would definitely warn you against outing him to everyone for the reasons others have already mentioned. However, you have already stated in your second post to the thread that you aren't going to do that so I suppose it's a moot point. Whatever it is you decide to ultimately do or not do about Shithead, (aka your abuser), I will understand and respect the decision. I just hope you will keep us posted on the situation and keep yourself safe. Take care. Peace,