I say go to the meeting by yourself Thursday. I think you could really use it and it will give you an opportunity to share with her all the good things your H has been doing the last few months (before OW stepped in again). More than likely he is going to focus on a lot of bad things during his C so if you are able to share with her the good things I think that would be beneficial.
Also, remember when you did that relaxation class? picturing those bad things put in a box or something? Why don't you go to that again. I think it really helped you detach last time.
I definitely agree to be calm, non-emotional in your responses to H about texting or whatever to OP. Just say, "You already know how I feel about your contact, but I have realized that I have no control over that and I'm not going to let it control my life again. You know my answer, but ultimately, it is your choice to make not mine." and then, like SD said, leave and do something for yourself to control your emotions and get you back on the right path.
Me 33 H 34 S9 S3 M 6 yrs (2gether 11 yrs) EA/PA 1/2006 DB 5/2006 H wants D 6/2006 H wants ME 8/2006 H "said" PA/EA over 8/2006 H erased OW off phone! 2/2007
"It is far better 2 choose humility & change oneself, than 2 wait in vain trying 2 chang someone else."