B, doing nothing or taking action will not change your M at this point. I absolutely regret not following the advice I was given here and by my attorney a year ago regarding finances. I was paralyzed with grief and fearful that any action I took would push my H further away. My kids were devastated and I felt responsible because my H was spewing regularly that this was all my fault. In the meantime, my H was partying, dating, gambling and making expensive purchases with community funds. He wasn't giving any thought to what I was doing either way.
During the same same I was just breaking even each month. I was determined to keep the mortgage and all bills current to preserve my credit and I don't regret that for a minute. However, if I had gotten a support order immediately and the money was deposited into my own account, not our joint one, I would have been able to refinance my house much sooner. In addition, bonus money that my H received would have been paid in accordance with the support order. Now I may never see it and it's a very large amount. Receiving it is the difference between being debt free and not. By not taking action I hurt myself financially and caused myself a lot of unnecessary anxiety.
If anything, once your H is hit with what his choices are going to cost him he actually may start rethinking his decision to leave. I don't believe it would have made a difference in my situation, but in yours, who knows.
I know this is hard. It's horrible being in a contentious situation with the person you thought would love and protect you forever. When you are ready you will take the necessary steps to protect yourself and your kids. Your H might see it as taking action against him, but that's not true. You can take care of business and still practice DBing. Don't let this situation change you in a negative way. You can be both strong and loving. In fact, I believe that a woman who respects herself is one that can be trusted. Ultimately, isn't that what you want your H to see?