Hey 7Knots - I am glad you found your way to this community. Boat, Kind, and Steve are all offering you very sound advice. You are doing many things well. Having some doubts is common too and happens to most of us.
Regarding OM, you have set up some boundaries and, to me, you would do well to tighten them up. I recommend something like "As long as OM is involved, I will not 1) share a bed 2) be more available/connected 3) FILL IN THE BLANK(S)". Note that I did not use the word "you" in reference to her. You can only control yourself. Using the word "you" with a spouse who is wayward, in a MLC, experiencing mental health issues, etc. can be like pulling a trigger that is likely to elicit negative responses. The bottom line is that until these behaviors stop, you are unavailable as a H. Be an acquaintance, offer the basic courtesies you would to one, and focus on doing what you can to (as the beer commercials used to say) be the world's most interesting man.
The boundary may include something like "I will not be a solo parent and need a partner who will respect their child(ren) to be a present, loving parent". As noted earlier in this thread, especially if you're in a "fault" divorce state instead of a no-fault state, document, document, document. Keep texts, emails, etc. in case you need them to help you with custody later. Talk with your L to confirm what is best because I am not one!
As far as DBing, you likely read that this will be a long process, will get worse before better, and prepare for either outcome 1) piecing and a long reconciliation or 2) divorce. It stinks. Some of us tilt more towards 1 or 2. I'm with MWD: if it can be saved, marriage should (unless there is abuse, drug use, and so forth as noted in DB and/or DR). You shouldn't stay together just for the kids. Kids should be one of many important reasons people work to maintain a healthy marriage. I also recognize that there comes a point for each of us when D is the best course of action. We each need to arrive there are own way. I wish you good luck, sustained support, and the best holidays possible under your circumstances.
