So, my W goes on these "walks" around our neighborhood where she meets her EA partner. I know this because I've seen the texts. So far I suspect it's just an EA, but things may have escalated to a PA. Do I just let it slide and not say anything? She doesn't know that I know what she's up to.
The affair is your enemy. You do everything reasonably in your power to end it. You absolutely do NOT give it a chance to grow and blossom. How you go about doing that depends on who you talk to (If you believe you have a "Wayward Wife" (or "WW") then look for Sandi2's threads on WWs) but from my personal experience and from what I have read just sitting around waiting for it to end is NOT the way to go. Affairs will often get "stronger" and more ingrained as they go along. I found out about my own W's Affair reasonably early, before it had grown too profound, and prolly had a chance to stop it much more easily and with potentially much better results, but I got some conflicting (and some bad) advice and allowed it to continue and after a point it went from a curiousity/attraction to a full blown infatuation/love-affair kind of thing, which, while my W has now apparently cut contact with OM, still casts a huge shadow over any efforts to reconcile or work on the marriage. While we may not have reconciled even IF I had succeeded in stopping the A earlier, I am absolutely, 100% certain that my MR would be in better shape now had I moved to bring about an end to the affair sooner. You simply can NOT work on a MR while an affair is ongoing, and every single marriage counselor and relationship specialist will tell you likewise.
Do yourself a favor-- do some crash course reading on this site on handling affairs, particularly WRT establishing "boundaries", think about collecting some intel (yes, "snooping," although opinions vary on this and you need to guard against it becoming obsessive) and then, when you are comfortable with what you know and what you should do, ACT. The post just above this one offers some good guidelines if you do decide to confront your wife. I am definitely not a fan of just "riding it out" , particularly if you catch the A in the early stages and have a chance to stamp it out before it gets to serious, but... if you do decide to act, make SURE you are confident and comfortable in what you are going to say and do, and make sure that if you do establish "boundaries" that you are prepared to act on them. (Another mistake that I made-- not being well grounded in DB-ing and the corollary materials like Sandi's WW stuff before I acted.)
H53/W51, R-ing 4/'18
"Do not arouse or awaken love until it so desires"-Sg.of Sg 2:7
"So oftentimes it happens,that we live our lives in chains, & we never even know we have the key"-Eagles III 1:3