I know it feels like the most important thing in the world is exactly what and how you say things to her. Valid arguments can be brought forth for supporting her because she is reaching out to you as a friend on a fear she has, and showing strength by not allowing her to disrespect you.
I want to suggest you turn your back on the whole argument. It does not matter right now if you are nice or mean. It does not matter what you show her right now. There is absolutly nothing you can do or say to change her in any way right now. By worrying so much how she will react, you are making this last longer for yourself.
The way you feel will drastically change when you put in the blood, sweat and tears it takes to keep your focus solely on you. You have some fan-freaking-tastic goals and things going on in your life that have nothing to do with her. Obsess about them.
I know you are not 100% there yet, so here are a few words of advice to get you through, but the following paragraph should not matter to you if you can get the focus on you.
You do not need to be cold, mean, happy, dull quiet or anything towards her. Treat her like you would treat your next door neighbor, but dont allow her to talk to you about OM or moving. Change the subject or walk away if they come up. Talk happily to her about your life or hers and just when the conversations are getting good, leave to do something important for you. Leave her wanting more, be mysterious.
I can tell from your posts that you are going to get the hang of this, I promise. Please, please dont read my post as criticism. You are brave and strong for just being here, fighting the good fight for the most important thing in your world, your marriage. If I did not believe you could do this, I would not have bothered saying any of it. You can master this with a lot of practice and patience.
Me: 42 H: 45 M: 18 yrs T: 20 yrs D: 17 D: 15 S: 12 I kicked him out 8/21/15 I will DB until March 21st 2017, that is it!