Like everyone else. Yelling, fighting, begging, pleading, exposing it to everyone, labeling her a harlot...etc. ad nasuem. You lay down a boundary that goes something like this: "I demand you stop seeing him." and ...what? She stops? She tells you she stops? Lets just cut all the lying crap out right now...she lies to you.
However, I suggest that instead, you work on yourself get yourself to a place where you are armored and can react clearly and without emotions running your choices, once you are there. Then confront.
The proof of an affair will happen, and you do not even need to look hard if one exists.
Puppy and I ARE on the same page for most of the advice about the affair...we differ on the immediate timeline at first.
I also fully agree with Pup about the absolute callousness your wife displays toward you, especially with her past affair.
GH,
I suggest that you continue as if there is an affair, get to a place where you are "GOOD" mentally and where you are strong DBing again...and not this...newb before you throw down a boundary or let your emotions make decisions your may not logically want or be able to enforce.
Pup, has my respect for being one of the few of throwing down a boundary and being able to stick with it...most cannot, most lack the back bone to live with the boundaries they impose.
Experience is a brutal teacher, but you learn. My God, do you learn. - C.S. Lewis
Life is usually all about how you handle Plan B. - Jack3Beans
Listen without defending; Speak without offending - FaithinAK