Sometimes people in MLC want to hurry through and get a D b/c they have the "grass is greener" sickness and if he has OW to push him then he may start that sort of talk sooner than you expect. Just do not do anything to make it easier for him to get a D. By that, I mean that he has to do everything. You don't enable his affair or getting a D. I would want to discuss what he plans to tell the children and certainly be there when he does any talking or you may be very sorry you aren't. People in MLC are not in their right frame of mind and they will make you come off a looking as bad as possible b/c they try to justify what they are doing to the family. So, stand up for your rights and protect the kids.
I don't know much about the legal side of what you asked before. Thankfully, I have not been down that road, but I think just b/b they file does not always mean there will be a D. In most states, it takes time. So, condiser time on your side. You have done very well so far about catching on to talking about business only and show your stength when talking to him. Don't break down and don't talk about your R with him. He has to have time to let this A fade out. Wheather you are still interested in him after he gets through with the MCL and the A, etc. may be a different story.
Take care, Sandi
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!