The risk though, is that you get no real intel other than the fact that they are texting, and you are showing her that you won't do anything about it even if she is doing it in your face.
What intel you know there is interest between the two of them so naturally they will communicate and find every means to communicate so why make it easy for them? All you are doing in mind reading and driving yourself crazy with sopeculation and your mind is your worst enemy in that regard. I remember all of the intel that the CIA, M5, Russian Intel about Saddams WMD....
You need to remove yourself from the sitch before you get wrapped around the axles. Focus on the things that you can control. Believe me it took me forever to understand that, but as you do you get more clarity in your situation and respond more objectively as though you are outside looking in. That is why many are telling to stop spying cut off the text msg. It serves many purposes. 1) helps you to stop fixating on the sitch and instead focus on actions to make you stronger. 2) shows your W that you are taking charge and won't tolerate her CB. 3) cuts off the free communication access.
Plan something with your son on Sat and go out at night with friends...live your life!