The current affair, in all likelihood, will end. You have statistics on your side.
The problem is, unless the wayward spouse addresses the reason why they would have done such a foolish thing, and unless BOTH spouses address the conditions that might have led them to the brink, it's HIGHLY likely that it will happen again.
So I would encourage you to focus less on the current OW, and more on YOU, and on your MARRIAGE. The current OW is just filling the current role in the script.