Only you know how much intel you can stomach. I had to stop several times, because it wasn't giving me anything new, and it was killing my confidence -- confidence I needed to pull off my "Man-o'-Steel" routine.
Periodic, routine checks should suffice. I'd look for her mood swings, and if she was suddenly happy, I knew there'd been contact. If she was suddenly depressed, I knew there was trouble in paradise. I also used the snooping intel tactically, to let me know what it was we were doing that was "getting" to them, and what I was doing personally that was working.
Wanna talk about difficult? Try listening to ACTUAL AUDIO of your wife, making out with another man, and telling him how "good" he is, after she's been sexually unavailable to you for three years. Ugh.
