What do you think you would do if he is there and your W and OM keep looking at each other? What if you see her looking at her phone? You know you'll wonder if it's him. What if both of them are missing out of their seats...at the same time?
As much anger as you've had lately, you have to think about this before you just take off to a place where both your W and OM see each other.....especially the first time they see each other after his W made her threats. Of course, he may have told your W to just play it cool in order to get through it. I hope he has been scared straight by his W, but IDK. A's are a powerful addiction.
I believe you're in for a miserable time. I think she may want you to tag alone for her protection from OM's W, in case she gets her a$$ beat. If he shows up, (and I think he will), I bet his W will watch both of them a lot more than she'll watch the game. You would be wise to not even look out the corner of your eye.
With hope and a prayer, there will be no incidents, but I bet there will be four adults there who will find it a little difficult to focus completely on the game.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!