Great topic, Lisa..in re to the initial topic and a few others, my 2cents..
Shantilly, I too would strongly advise the same thing...let the MLCer move out. This helps in so many ways, for me, it helped keep my life a little more stable in a world that was turned upside down and did the same for my children. But I don't see anything wrong with the LBS filing for the divorce IF there is an OM/OW (read below). Now, if there is no OW/OM - then you should absolutely be standing. We signed up for good times and bad - well, these are the bad. And I don't know about your state(s) but divorce all too often seems like some chaotic court trial that costs tons of money. I did a simple dissolution, no lawyers - just paid filing fees, submitted our own parenting plan. Now, I know that's not for everyone. but I couldnt imagine going through an actual divorce with court dates, and lawyers and motions. ugh.
Divorcing as a standing action? you betcha. Here's my view on that: now, I think there are some differences between male/females in MLC. Most women seem to be gone. They drop the bomb, and dont turn back. If they part with one OM, another is around the corner. Seems the guys tend to come and go a little more, they're on again/off again. So, standing and not divorcing - or trying not to divorce - might differ from what I'd do differently (which I didnt do initially) which is to divorce asap. It's one heck of a boundary and many of these MLCers are unstable and make bad decisions. Mine was drinking a lot. Didn't want my childrens futures ruined because of her mistakes that I'd have to pay for. And while I didn't want to end my marriage, I couldn't be married to her while she was with someone else. I believed that I WAS standing for my marriage by ending it. Again, she's with someone else, so I basically thought I was disrespecting the sacrament as much as she was by remaining married.
In the end, you need to figure out what you're standing for exactly. I chose to stand for my family, we're a man down (or woman rather) but - back to the moving out part above - we're still here in the 'ol marital home. I have custody of my children and we pretty much continue to live the same lives we've always lived. I consider myself 'standing down' right now for her, but who knows what the future holds. I forgave her a long time ago and still care deeply for her and always will. I knew I had to start moving my life forward and move on (and I don't think moving on means moving on with someone else) and if she wants to catch up to me, that's her job at this point. And if we did reconcile - our 1st marriage/relationship is done. I'd be starting a new and different one with the same person.