Is that a typo? Your S is angry, or your W is angry? Not sure what is DB way but I'd probably talk to her about it and validate her feelings, but avoid giving solutions or discussing the overall marriage.
Your W being upset after your encounter w/ OM makes sense to me. She's intoxicated on this fantasy of setting up a parallel life w/ the OM, and seeing you and OM having a friendly, comfortable exchange disturbs and intrudes upon her fantastical view of the world.
I think it's good that she's upset over it. It's good for her to realize that something is wrong w/ the picture as she sees it.
Me: 50, MLC/WW 45 Young kids Nov 2015: BD1 Apr 2016: BD2 Jan 2017: W filed Feb 2017: D final