DG,
I may be mistaken but I sense that you are willing to R but don’t know how to do it, don’t know how to forgive her, as long as you don’t know what you should forgive her to fix the marriage).
All I can say is that, based in my own experience, being stuck is slowly killing you!
Thinking about giving R a try but not knowing how, thinking about split but not knowing if that was the right thing to do… was the hardest thing I ever faced. In my head was a mix of ideas and feelings about love, resentment, anger…very exhausting.
What worked for me was closure, accept the things that happened, accept that all I know was not enough but there was a no way to know all that happened, and the most important thing: She was not who I thought she was…
IMO, getting closure is about saying what you need to say to who you need to say it.
Your next MC may be a final tramp to take you to the cleaners and taint your name, I doubt it but I have seen worse, or maybe the same as 1 and 2 meetings, also very unlikely as haven’t work so far, or a much more strong try to keep you attending MC, very bad idea with this MC, or anything else.
I believe you should tell your WW at the next MC what is in your mind, not the anger, not insults but facts:
The disappointment your feel, for the lying, for making you feel mind sick and letting you ask for help when you were right, etc.
Not coming clean was driving you nuts, and pushing you away,
Not right involving your Daughters,
Not right involving a lot of people,
That even if it was just an EA, she going to a motel to meet him says a lot of what she was willing/wanting to do.
No matter what, she is the love of your life but can be together anymore, at least until all cards are on the table to know if you can give her a chance to try R.
You want the D to be civil and amicable for the Daughters.
Etc.
Then sit there and wait for the MC to finish for her to give you the PS.
No matter if you cry, no matter if she cries as well, all that matter is that you can take all of this from your chest to start healing.
Just another thing BE CAREFUL TO KEEP THE ANGER UNDER CONTROL, if you lose it this time you are not going to get the PS and they will have a perfect excuse for not giving them to you. Use your phone as a VAR even tell them that you are recording the MC meeting.
Good luck