First - I want to say thank you to everyone who has replied to this and offered me their sincere honest advice - it is very much appreciated, and it helped both myself and my wife tremendously.
Second, I apologize for the tremendous delay in my reply, a lot has happened since then, and I felt I owed you all an update. In any case, I felt like posting one. Discussing this has been... cathartic, and very beneficial.
I gave her my blessing to continue seeing him, at least until I returned from my trip to California. I think she respected this decision, and understood that it wasn't an entirely easy one for me to make. I did my best to take the high road and be as understanding and supportive as possible. I know now for certain that what Red Pepper said is pretty right on - it was just about the lusty sex, and the release of pent-up sexual energy from my absence, as well as the new excitement and energy that is standard with discovering a connection with a new person.
You'll probably recall that we, being fairly responsible people the vast majority of the time, decided it would be best if she got tested for STDs, since she succumbed to drunken passion and threw caution to the wind with unprotected sex. Well, as it turns out, my instinctive mistrust of the guy was well justified - he did give her (and I) an STD, or more accurately, an STI - Chlamydia. Thankfully, that was all; no other tests have turned anything else up, and we will be getting tested again in several months to rule out anything else for certain. We have both been treated for it, which was very simple and painless, except that it prevented me from being with my own lover again before I left for home, since I had not been with her since being with my wife. She got tested, on the off chance that she was the source of the Chlamydia (or her husband), and was of course negative for any and all STDs, as per her previous tests.
Well, needless to say, I was furious about this, not with her (I'd already been through that and forgiven her for taking the risk), but with him for putting my loved one and myself at risk through deception and habitually risky behavior. At that point it was painfully obvious that he had indeed been with other people since being tested, and hadn't copped to it. At this point, he had left for a two-week trip to Europe, but was still in touch with her via text and email. I informed her that she needed to end it with him, period. She was slightly reluctant, it being a fairly minor STD, but she agreed, doubly when I reminded her that it could just has easily have been something completely life-altering. Needless to say, we fought about this - she wasn't as mad as I was, which just made me angrier, and made me wonder what her malfunction was that she wasn't
. This was compounded by the fact that several days passed and she still hadn't contacted him to end it. Ultimately I came to the conclusion that what we were witnessing were my protective male instincts seeing this as betrayal, vs her nurturing female instincts reacting with disappointment rather than fury (she likes bad-boys; if she didn't, she never would have fallen in love with me). Finally, she sent him a message saying it was over in a far kinder way than I would have, and he replied with how sorry he was, blah blah blah, he'll miss her, cherish their time together, yadda yadda. Apparently the message wasn't ENTIRELY clear, because he contacted her again once he returned from his trip, asking if she would join him for dinner. I sent him a text advising him against further contact with my wife. We haven't heard from him since.
We have, however, had an incredible boost to our sex-lives with each other, and I've realized that I need to work on being a better lover now that the bar had been risen. Well, I've been working on it, and we've been having great sex every night since I got back (a month and half now). We haven't been with anyone else since, and for a while, she was in favor of going back to straight monogamy again because of the drama this has caused, until I reminded her that we were both going to want to experience other people at some point again, and that most of this drama could have been avoided with a little more diligence - in the future, it will be safe sex until trust has been established. So, as it stands, we're both open to other lovers still, but haven't been with anyone else since. She has stated that since it's so much easier for her to find a lover than it is for me (admit it, girls), that she wants to wait to take another lover until I have found a new one myself. I told her this isn't something she has to do, but it's what she wants, so I'm ok with it.
As for me now, I'm really starting to wonder how the heck poly dudes meet women! Seems like most ladies want a baby-daddy of their own to keep, and I can't really be that for more than one person. Furthermore, most women won't go near a married guy with a 10-foot pole, and I'm not about to lie about it. I met one woman who seems to be into me, and we've emailed just a little bit back and forth, but because of her busy schedule, we won't get to do any real hanging out until mid-December. We haven't talked enough for the subject of status to come up yet, but she does know I'm a Dad at least, I had the boy with me when I met her. We'll see how it goes, if indeed it goes at all.
Edit: Some other things we've learned from all this... My wife needs me to be a little bit more assertive in our relationship and take a more commanding role, without making her feel inferior or that she's not my partner. This is a very weird and thin line to walk, because on the one hand, she needs that strength and leadership from me, but on the other hand, she's very much a feminist and not into "submitting to a man because he's a man" - something I would never expect because I've always viewed as us partners and don't believe that men are inherently somehow supposed to be in charge. However, she won't respect a man she feels is weak, and I've had to remind her (and myself) that I am not a weak man, but one that deserves respect and admiration, from her, and in fact from everyone who has known me. This seems to be working - and has helped restore my confidence, though sometimes it feels a little odd to do things in a slightly different way, slight though the difference may be.
I've also been exercising a lot more - lifting weights and boxing, which has helped my confidence... Also, the improvements in my body have driven her wild, which is never a bad thing.