You are right to be concerned about your son. Based on your actions, you seem to be still most concerned about your WW. I think you should work on redirecting that concern to your son because this situation is really, really bad for him and he has no recourse or protection right now.
One thing you do have is some leverage over the school district. Your son is basically in a hostile environment due to the actions of their employees. You should be able to get them to accommodate requests to change schools or whatever else because they know you/your son could legitimately sue them if they refuse to address this hostile environment. Are you at the same school too? You could both move schools, but my concern is that news like this will follow him/you around to nearby schools, especially with you guys involved in sports which helps spread rumors between schools. I would suggest you seriously look at moving to a different school district ASAP.
And here is something I personally believe very, very strongly is the absolute most important thing you can do for your son - you should tell your son the unvarnished truth about what is actually happening. Knowledge is power and right now he has no power over his own life. Most likely he is in the dark and putting together things from rumors. And like the stereotype BH who is the last to know, all of his peers and teachers talking about this behind his back only further isolates and humiliates him.
Lots of people say that its the lying more than the infidelity that kills a marriage. Well, I'm not a child psychologist in any way but from my experience it is also lying parents that is most damaging to kids. And you purposely withholding this information from him is not protecting him, it is lying by omission and commission. You are taking away any bit of control and self-protection he could have, and instead you are inexplicably providing that protection and control to WW and OM. I believe that kids, especially older kids and teens need at least one parent/authority figure they know they can trust because kids have limited control over their own lives, they need the security of knowing that someone with this control is looking out for them. He knows he cant trust his mom right now - that's something lots of kids can deal with and get over just fine because they still have another parent they can trust. But if you are trying to snow him over too, then there is no one he can trust and the world is a much scarier place.
