No more driving by their house. Stay the hell away from W and OM. The OM is nothing. An annoying gnat.
They are in the flush of an A and their heads are messed up. Look at how your W is 'farming' out her parental responsibilities. She is not being sane or rational here.
You need to be the rock to your kids and be the sane one. If you go batchit, then the kids have no strong adult models.
Stop this chit. Want to stop feeling "exhausted", then stop looking in W's direction (both literally and figuratively).
What are your GAL plans for the rest of this week and weekend?
And I do have to say this: Be the real grown up. Don't have your son see you driving by the house like a Peeping Tom. What sort of example are you setting to your kids? Most importantly, what kind of cop are you? By exhibiting those kinds of behaviors, it doesn't reflect well on you.
Detach. Focus on YOU and the kids. It's the only thing that you can control.