It sounds like you know your M is probably over unless OM suddenly dumps her. Gucci is right - he may be lying to your W. You could still shake him out of the tree if you expose this to his W. It is probably your only leverage at this point assuming he hasn't been up front about it like your W was with you (so to speak anyway - she is separated and told you she wanted to date OM so you shouldn't be suprised).
He has to dump your W - it is the only hope you have. It still might not save your M, but if you don't want this guy around your kids etc that should be your motivation at this point (not revenge, etc).
I am settling into the same place. My W is moving out, OM is a factor, and my main concern now is that her R with him fizzles out because this guy is trash and I don't want him in my kids life. I would almost be relieved if she found someone else at this point. I tried exposing him to the woman he lives with already and not sure it had an effect. You may have better luck.
ME/XW:47 S21, D19, S15, S14 M:21 T:26 W moved 6/10 I filed 7/10 D final 4/12 remarried 8/12 W wants to R 12/10 and 4/11 but I decline
