I've given my thoughts to Jennifer offline, but I wanted to comment on SD's inclination to print out the email & have it ready for 'pouncing'. . .
First, I can say that I DO understand that inclination. The shades of lies and denials on the part of S. are infuriating and hurtful. HOWEVER, as I told J., do you want to be RIGHT or do you want to be HAPPY?
I believe she IS right in that S. is not being honest and his actions are damaging to their relationship. But I don't think confronting him will actually make him deal with his lying and denial. It will more likely make him defensive AND project his guilt & anger on to Jennifer. It will give him cause to say "see, she's so controlling. She's a snoop. This is why our R. isn't working." I truly believe that there is little J. or anyone else can do to make him confront his actions and the consequences of his actions, UNTIL he is ready to do so . . . When lying stops working for him, he will be able to consider why he does it, and how he might want to change that behavior. Right now, if he does it, it must be because it 'gives' him something. What that something is remains to be seen, or perhaps it's something he's afraid of 'losing' if he tells the truth. Either way the answer is within him and my guess is that it will take some very careful navigating to get him to open up.
I also think that confronting him will likely make the comparison between Swiss Miss (SM) and Jennifer more glaring in his own mind. SM will remain in that fond memory (fantasy) category and J. will be the irritant in his life. So my advice was to hang tight to the information for now, deal with these big issues in therapy (since that's where S. does seem to be able to listen & understand issues better) and to not react from her hurt and anger right now. I thought it best not to play into that difference he might perceive between SM and Jennifer.
Is it fair? Well, no . . . but given the situation in which J. & S. are about to become parents, I think it might be wiser to cool off some, consider the long term effect of their actions and work on being happy rather than right. This is not a simple issue and in my belief will take some considerable time to unravel... Ugh!
I know this issue of Lying quite well as my SO is a Lies of Omission guy too. It frustrates the hell out of me and has been quite painful at times. Only very recently (within the last 2 weeks) we have been able to have a decent conversation about this topic. He is NOW more able to talk about it and admit that he does do this to protect himself, and to protect me - or rather my image of him. He is slowly getting that it does exactly the opposite - it tarnishes my image of him. It is a slow process. He has to learn that telling me the truth is OK - that it may be painful at times, but not nearly as destructive as when he chooses to lie about something. That requires incredible effort and patience on my part - resisting the urge to clobber him with "The Truth" and waiting for a calmer moment to expose the consequences of his dishonesty.
So in the end I'd add a third choice to SD's list, which is to do what it takes to break through the denial in a gracious, non-injurious, slow manner. The idea being that you want to help work on this issue together, not simply point out his shortcomings.
