This is not looking good! (Long post...)

[Accuray]

Mab1

ScaredSilly is spot on. You are also right that MC will go the same way. It won't go as far off the tracks because you have a moderator, but I can guarantee that W won't leave the session feeling good about you.

Almost every time we've spoken since she left it starts well and then rapidly goes downhill whilst she tells me how much better life is without me.

There is NOTHING you or MC can say to change her mind right now. The key phrase there is "right now". Things will get better and she will rethink things but not on your timeline. You are acting from a place of panic, you feel like you are drowning and must get to the surface right now, so you're trying to grab onto her with everything you've got. Let her go, that's your only hope of having her come back.

Problem is the going dark alternative seems a bit too one sided. She gets all the freedom she wanted and I worry about rebuilding my life.

This is key Mab1 -- this is completely one-sided and there's nothing you can do about it. You can't fight that, she feels she owes you nothing, she is no longer your wife. You don't get to dictate how much freedom she gets, she will take what she wants. You can't stop her from dating new people, and you can't demand that she work on the marriage with you or even talk to you.

You need to become a good choice for her by working on YOU. Following DB will give you the best chance of having her notice your changes the soonest, including going dark. These things are counter intuitive but they work. You really need to shift your perception. You are now on the outside and cannot talk your way back in. She has to look out the window, see how much fun you're having and what a good guy you are and want to join you

How can I keep the
communication lines open without seeming to be pursuing?

When she reaches out to you be polite, be happy, and validate her feelings but stop short of agreeing that your marriage was all bad or that everything was your fault