Just keep going Ken, she doens't want to leave, that's a good thing... you have to push her out of the open marriage setup she's steered you into...

No more pleasant choice a, your wife now has to choose b or c remember?

Just keep pushing her in those directions.

The other thing you could have said when she protested about you "kicking her out" is

a. I am not kicking you out, YOU are choosing to destroy a marriage rather than to rebuild one
b. I need someone who I can rely on as a parent and partner... YOU were supposed to help with these kids, but you were too busy on the phone with OM instead... You're a crap mother