Also realize that your W is a person, not property. She can do whatever she likes. However, in a M there should be a reasonable amount of transparency and you should ask for that.
Respectfully, I disagree with this. If she wants to be with another man then she can leave the marriage. Marriage is a contract and while she's not property, there is a way to end things honorably. Problem is she's so lost right now she won't hear you. You can shake her up by giving her an ultimatum: him or me, but you need to be prepared to act on it. That will mean separation if she won't comply (ie. unfettered access to the blackberry, no contact with the OM and a written no contact letter, disclosure of all details, marriage counseling).
As for the illegality of spying, I think that's the least of your problems. I'd spy. You have a right to the truth.
The DB approach to toughing it out seems a bit unreasonably to me. When I discovered my ex's A, I immediately triggered separation. In retrospect, I should have calmly stated that she needs to be married or leave and given her the option. (It wouldn't have made a difference.)
Even if she agrees to stay, expect that it will take a few months of lying, broken no-contact, etc to really take. If she leaves, expect a massive amount of bullshit, "we're just friends", etc. That's when you really need to pull out the DBers stuff as stay silent, strong, do a 180, etc.
It doesn't sound like she'll stay, though. Hopefully I'm wrong. Sorry bud, it [censored] sucks. You're in for a tough ride.
I don't care, then I do, then I don't, then I do... la de da
