As to the voice recorder, cell phone spy software etc. I know that knowing has helped me get to the truth about this but I'm not sure how this helps if I keep digging further and further.
The first thing that cheaters do, is that they will deny and deny, and minimize. Upon being confronted with evidence, they will then only admit to what you know. This is like seeing the tip of the iceberg. This is called Trickle Truth.
I see from your other post, that OM is local, since you've had him over for dinner. So how exactly do you know that this is only an EA?? Do you have the proof? Is this what she told you? You know how many hundreds of stories that we've read here, that the WS first only admits to an EA, then come to find out, they held hands, and then it becomes hugs, then it becomes kisses, then it becomes oral, then the BS finds out that it did go physical so the WS says they only did it 1 time, only to finally find out that its been going on for some time, and they've had unprotected sex many times? I know you're a new BS, so the disbelief and denial is strong at this stage.
I've only very rarely seen WSs only have a PA, especially when their AP is local. EAs very quickly progress to full on PAs.
I think that now that its out in the open the odds that she would slip up (Assuming she decided to continue on) is low and the odds of her picking up me snooping and turning that around on me are great.
And this is the one of the MOST common mistakes, the newly betrayed like you do. Simply ASSUMING that on DDay, the WS won't do it again. Experience has shown that many WSs take the affair underground. They simply find another method of communication.
You need to understand how affairs are an addiction. They rarely break it off right away. At least one of the affair partners will attempt to renew contact. This is called fishing. You're assuming that you're wife is rational right now. When they are in the fog, they are not rational and will make irrational decisions.
You also need to get this idea out of your head that it's wrong to snoop. She cheated. You now have that right. Did you even click on any of the links in my signature? Check out the Betrayed Spouse Bill Of Rights. If she can turn it around on you, then she's not remorseful about the affair and the likelihood that she will do it again, are great. I like to call it verification.
Verification serves 2 purposes: It ensures that the WS has honored NC, the affair is over, and that you will be detect any fishing between the two of them. The second purpose is that it helps rebuild trust. Of course, you cannot tell your WW that you are checking on her.
I'm not sure what writing her a no contact letter does that having it out in therapy and at home didn't do. Is this for some future legal action because that is not what I'm gearing up for.
Writing the NC letter establishes a clear, written boundary that she will not contact her OM, and he cannot contact her, and if he does, she's breaking NC by giving you a lie of omission. I certainly hope that you're one of those guys who think that therapy is some magic pill that cures all.
Ok, that all said I recognize that I'm new at this and probably making some mistakes that others have made. Hopefully you guys (and ladies) can slap me upside the head a bit if this sounds too stupid a plan.
Yes, you're new at this alright, so you may need a 2x4 or two. Some posters, including myself, have links in our signature, you would do well to make use of them. Also, you need to hang around a bit more and read the threads of others, not just your own situation.
I've noticed that you've been VERY skimpy on the details of your situation. If you want help, you're going to have to be a bit forthcoming so people can advise you. Almost EVERYONE here has been betrayed and is going thru something similar to you. This isn't some random forum on the net. The others here who haven't been betrayed are former cheaters, and give valuable insight from being on "the other side". There are also those here who have been on both sides. You would be helping yourself a great deal by availing yourself of everyone's experience.