The CF does not have any explicit legal involvement in infidelity that I know of - the Yanks do, and have regularly prosecuted folks for exactly this situation (I read about a Col from Strat Bomber Comd who was taken out for an extra-marital affair with a Pte)..
The issue of consent is the key here - the actions between the 'WO' and the 'wife', both consenting adults, are probably not going to be relevant. If said WO was to at all make any comments to you at work, or treat you in a fashion that differs in the slightest from all the other subordinates, then it becomes an issue for the CF.
I would also wonder if a NDA Art 129 could be used, in that such conduct is clearly prejudicial to the maintenance of good order and discipline within a unit. Somehow, I doubt that the rest of the unit is unaware, so it has probably been discussed, and impacts on how the WO is perceived, and perhaps even obeyed. I had to deal with a 'wife-swapping' free sex group in a unit, and had a 2Lt tell me that what happens off base is his business. The advice I rec from legal was that once troops within the unit are aware of it (they were), and it begins to impact upon order, discipline and even morale (they all hated him), it becomes a CF issue to deal with.
Let the system deal with it properly, but for your own sake, see the Padre or other resource.