I sense that you are still feeling combative, attached, and, ultimately, controlling.
Yes, your W seeing an AP is wrong, and you should not tolerate it. But there is a difference between setting down a boundary, and trying to assert control and emitting hostility.
I of course understand why there would be anger, hostility and resentment. Hurts like hell.
But in terms of what's going to work for you ... I think you have to totally set aside hostility and a desire to MAKE your wife do anything. Let her know what your boundary is, and then step back, waaaaaaay back, and let her choose to do what she wants to do.
You could see the therapy sessions as half empty, but I see it as half-full. It's a gift, man, and gift that 95% of here do not get.
Use it wisely.
Me: 50, MLC/WW 45 Young kids Nov 2015: BD1 Apr 2016: BD2 Jan 2017: W filed Feb 2017: D final
