You are right, time is your friend. You are right not to want to live in an open marriage as well. Get back on the horse. I understand those emotional moments and how they can knock us down. But they won't hold us down.
If she wants D, let her do the work. Start working on detaching today. No more R or M talks. Give her all the space she needs. Don't bring up OM at all. Let her focus on him. Its time you focus on you and not her and him. Back off all the way.
Tell her hi and bye, and only convo about the kids. After weeks and months of a change like this she will have no choice but to notice. But trick is, you becoming happy for real. Loving on your kids for real. Enjoying your life for REAL. No half a$$. You become positive. You start smiling and laughing around her. Telling silly jokes. She will test and try to bait you out of being happy and joyful. Dont let her. Keep smiling. Keep being happy. This is your way out. You are worried about you now.
M:37 W:37 T:11 M:10 S17, S13, S10, S4 BD:06/28/17 OM confirmed 07/20/17 Recon the M 10/29/17 Working hard:2gether
Onward and forward
This process is not a sprint it's a marathon! Patience, Patience, Patience.