I do not want to live in an open marriage. My problem is to find out the right strategy to achieve that.
I afraid that me being confrontational will make her go back to her old ways of not giving a damn. I'm torn between waiting it out, give her space and let the affair die vs setting firm boundaries with the risk of inviting more drama.
So, to be clear, your boundary is "I will not live in an open marriage, unless removing myself from that would cause more drama or will make my cheating wife not give a damn."
OK, got it.
Your WORDS to your wife say one thing, but she has learned to instead watch your ACTIONS, which are wobbly at best. So she's playing you. She will begin to take you seriously when you begin to take YOURSELF seriously, no sooner.