I'm so sorry for all you have been through. I read through some of your latest posts after reading your request for opinions on the Surviving forum.
It's been 3 years since my XH and I first separated and over 2 years since I found the DB board during our second separation. As hard as it was for me going through this, I cannot imagine how difficult it is to do this with kids. I think that added anger and resentment for their pain makes it so much harder so the mothers and fathers here always amaze me.
Anyway, while I agree with others that you cannot know exactly what your H will talk about on Saturday, I also know from experience that there are times you just KNOW what the general subject will be. Two years ago my XH wrote me an e-mail on my birthday saying Happy Birthday and can we talk on the phone tomorrow. Everyone said that it couldn't possibly be to discuss a dissolution/divorce and that I shouldn't assume but I KNEW that that was exactly what it would be. He had avoided the subject for so long and tried to broach the subject by talking about the "limbo" we were in. When he would bring up the "limbo" comments, I think he was trying to get me to say that I was tired of the limbo (I had lost my job 2 weeks before our second separation so I was sleeping on the couch at a friend's house for 3 months)but I wouldn't say anything. As far as I was concerned limbo was better than going forward with the end of the marriage!
That said, if you do not want a divorce, then stand strong on Saturday and be clear to him that you don't want it and you want to be a family again. Let him know that you missed having him in the family pictures taken with the kids. Let him know that you understand his frustrations with his life over the past few years but that you believe your issues can be worked out. There's no need (and it won't work anyway) to try to convince him of that so don't get sucked into arguing these points with him. You just need to let him know how you feel. Obviously he can still file for divorce anyway but at least you've expressed yourself to him.
Try to listen to him without arguing which does NOT mean that you accept what he says as the truth either. This one is hard for a lot of people. You don't want to agree with things that you don't believe but you also don't want to argue because that can drive them further into their own beliefs.
FWIW, I would also let him know prior to or at least when he gets there that you will be leaving at xx time if you want to keep the conversation limited.
Oh and most importantly, even IF this discussion on Saturday is about his "decision" to file for divorce, that is not the end by any means. Of course it's not good news but people can still "decide" to file, tell you they are filing and then still hold off. Or even if they file, they don't follow through. So remember this to help you keep your cool no matter what the subject is on Saturday. It's just a conversation and your marriage will not end immediately no matter what he says or does!!! Just listen and be ready to vent on the boards if you need to.
when the bomb first hit, H told me he didn't think I even loved him anymore, and that I didn't respect him. I was floored...I love this man so much respect him so much, have told him so many many times, have shown it in so many ways.
This is interesting. My friend's XH (WAH but no affair) told me that he didn't think his wife loved and respected him which shocked me because I thought it was so obvious that she did.
My theory is that it really is not about what their spouses do or don't do to "make" them feel respected. It's more that they are feeling badly about themselves WITHIN and instead of recognizing that they project that feeling onto others. Somehow someone else is supposed to "make" them feel good about themselves.
Still your point about being aware and seeing if there is a way you can make it clear in his language how much you love and respect him (at least certain things about him!) is a good one.
And finally, have you read Frank Pittman's description of the different types of affairs? I put a link to his article below. My XH's was a "Romantic Affair" and Pittman describes the trigger for these types of affairs as a "turning point" which is "any situation in which they must face a lot of reality and grow up." For my XH we had just started trying to have a baby about 5 months before the affair began. With twins and a little one your H might be feeling like he's facing a lot of "reality" and needs to grow up.