I wanted to add another thought. I think if it were me in your place, I would stay away from having public family outings like the meal you tried to have with your W and child. B/c of the condition she is in, she apparently feels this urge to bait you into an argument. There could be several reasons behind that, but my first thought is to give her more justification in leaving you. She'll say you are so hard and unreasonable to live with! So, in detaching from her, become less available to her as well. (Being around her less.....is good.) That means avoid these types of outings.
When she starts a talk about OM, tell her you are not going to discuss it. Don't argue with her. If she says, "Why aren't you going to talk about it?"........just walk away. She knows why you are not discussing it! I promise you that no good will come out of a conversation about her and OM! Leave it alone.
Arguments about everything will be easy to fall into at this time. Expenses, the kids, what people say about her, etc. Everyone's feelings are "raw" and it is like sitting on a case of explosives. The more you are out of her sight, the better. When you are home, it would be best to do things with the children. Keep them involved in something with you. The more they are in their rooms alone and on the computer or cells or tech toys, the more withdrawn they will be toward both of you b/c they don't know how to deal. They need to see their dad strong and dealing with this stitch. Along with your R with them may come need for discipline of them and that goes back to how they treat their mother.
If things get uncomfortable at home, take them out for a treat or walk around the mall or bowling.......whatever they like to do. The age your older ones are, it is vitally important to spend one on one time with them.
Got to go, 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!