M...you got this. Calm, cool, collected, very matter of fact. You didn't do all of this work for the past 6 months or so for nothing
Who was the one that requested the meeting? Did she ask you to come over and then you suggested a sit down? What gave her the idea you wanted to talk about anything? Or is it in context with you never telling her how you feel about the situation?
Obviously your not 100 sure where she is going to go with it but do you know what you want? What if through the course of the conversation you find out about OM? Is that a deal breaker? You have said before she would need to change before you took her back. What would that look like?
When I think about my W approaching me about our R I picture myself listening, validating and letting her know I need some time to process. If she asked me what my feelings where I would tell her I was initially shocked, hurt and angry. However once I was able to step away and look at things clearly I realized that I wasn't happy either. The anger turned to sadness, the hurt went away and I became more accepting of how you felt. Then I started looking at myself objectively and put all of my focus into my own happiness, my own self-confidence and then I realized that I am going to be happy with any outcome because I found myself. The time, the space, the distance allowed me to find myself and that is all that I will really ever need. Maybe not these specific words but something that let's her know your good, your not sitting their graveling, pining away that your a man of value and that you don't want to be with someone who doesn't want to be with you. Your not just sitting around.
If she asked me what would need to change in our R I would let her know that we need to work on our communication (I could give specific examples if needed), we need to spend more quality time together and put our MR first before ourselves and the kids, do more things together as a family and spend more time connecting individually. I would also say sex life as well but I think that is a product of intimacy and connecting so sex would probably increase as a result of being closer. So I am not sure I personally would bring up sex but I would need to think on it.
I also think your W needs to know your a different person as well. What if she asks you what have you been doing with your time? You could play it coy or you could just let her know. Maybe not in this meeting but as you go through the process. You enjoy rock climbing, your new home gym. some of the artistic things you have re-discovered and those GAL activities will be in your life moving forward. How have your expectations changed of her? What would you want her to do differently, your non-negotiables?
Again all of this may not come out in 1 conversation but just stuff to think about. I think this is also about your confidence level and do you feel as though your in a position to communicate your wants/needs/desires and do so with the understanding that she may not be able to deliver and if she doesn't you either accept her or you move on.
When I think about having this conversation with my W it makes it easier when I tell myself we are already D'd. We are separated, finances and time with the kids split what do I have to lose? Hell, I have already lost it.