Again I am not following the plan well at all but it is not like i am expert on this.
You seem to know something about Dr Harley's plan, because you mentioned exposure in your first post, although you said you hadn't done it properly or effectively. Have you read all the free articles on this site related to surviving an affair? Do you have access to the book
Surviving an Affair?
I think that, before you can go any further, you need to work out whether you are capable of following Dr Harley's plan for several months. I have my doubts that you can, since you seem to know elements of it but admit to not having followed it.
If you can follow the plan, it would involve completing exposure and following the rest of Plan A. It would mean trying to persuade your wife to move away from the area that you live in now. If I understand correctly, your wife and OM do not work directly together, since she is a police officer and he is a fire officer. However, they are able to see each other in the community. Therefore, if you want your marriage to stand a chance, you will need to move far away.
Who does OM live with? Is he married? And is there a more direct way of contacting his mother - can you find out her address? You can't let obstacles like Facebook stop you from doing the job properly - not when you are fortunate enough to know the identities of his family members.
Plan A requires that you put pressure on the affair through exposure, while offering your wife the opportunity of a different marriage altogether from the one in which extra-martial sex has been the norm. It also means waiting for the affair to finish if it does not end right away. Do you think you can follow a plan while waiting out the affair?
Do you think your wife is interested in a new marriage with you, after the sexually libertarian one she has had so far? You have given her permission to have sex with other people. She now wants to have sex with OM, without you in the picture. What do you have to offer that could make her change her mind about you?
Finally, do you want a marriage free from sex with other people? Why do you want it now, when you haven't wanted it for all these years?