I am looking over the other threads (and posted a bit) while psyching myself up for today's potentially final-ever meeting with STBX. Reading the other threads is helping me keep from psyching myself out.
Point the first: if I find myself prompted to say anything, all I need to say is "I didn't want a divorce, and I still don't, but I won't stand in the way of your decision; and as long as you are still with OM, I will not be your friend."
Point the second: if she has the colossal bad sense to bring OM along with her, I don't need to rant about the awful things he's done or the despicable person I believe him to be. Just "you're not welcome here", and withdraw until he's gone.
Simple, succinct, and as non-hostile and "friendly" as I can manage to be.
I think I'm generally in a good place about this, but as the time draws closer I feel nearer and nearer to wanting to puke.