I am alarmed that she and OG went ahead and fluid-bonded without discussing it with you beforehand. Seven months isn't really a long time to be involved before doing that. There are a number of tests that do not get performed unless requested, and many that require regular periodic testing to be (more) sure. Furthermore, she is not just fluid-bonded with him, she is fluid-bonded with the both of you - and that means you are at risk. Taking this drastic step without your knowledge, permission, and investigation of the "facts" (ie., have you seen his test results on paper? How recent were they both tested?) is flagrantly disrespectful to you, and just plain stupid and selfish. "Oh, by the way, we fluid-bonded a few weeks ago." What kind of crap is that??!!! And now you are in a position where, if they won't use protection, you should. Because they expect you to just go on his word, but since they didn't include you in the decision, his word is worthless, as I see it. That is screwed up.
If I were you, I would stand up for myself in the face of this dismissive and idiotic act, and NOT have him in your home interacting with your children until that breach of trust is healed. It is a serious thing they did!
But I think I will speak mostly to your last post.
Her communications to you have been quite unkind, and yes -- it seems there is an element of vengefulness or wanting to punish you somewhere in all this. You are trying to be a nice guy but you are in this poly situation when you really don't want to be. It does not seem like your feelings or need to perhaps move more slowly, were even taken into consideration. And now you are expected to just put up with whatever she wants, while your "seeking to avoid my jealousy, insecurity and possessiveness," as you say, isn't helping you one bit. Besides, avoidance doesn't really work -- ask anyone who drinks or uses drugs to avoid the pain of living. The pain is still there, just buried by addictions, and it never goes away.
You cannot avoid your feelings. The only way they can truly be "vanquished," that is, no longer rule you, is to feel those feelings as they come up, look at them, let your self be with what is, and not try to avoid it all. So, if you're jealous, fuck, that is what you are! It doesn't mean you need to lash out at anyone because of them, but avoiding them only keeps them around. "Whatever you resist, persists, and grows stronger." Once you allow yourself to be just as you are, those rages, insecurities, etc., will complete themselves and you will see things more clearly. Sure, they'll come up again, but the more you practice being okay with your emotional responses, the less power they have over you.
In
Journey of the Heart by John Welwood (a book on relationships which I highly recommend), he writes:
"Depending on how we relate to love's pain, it can lead in one of two very different directions. If we regard it as a threat, something to avoid at all cost, we will try to patch it over, keep it out of sight. After a while, however, accumulating patches only deadens our sensitivity and our capacity to love freely. Resenting the pain involved in becoming vulnerable to another person causes us to lose heart or harden our heart, and this cuts off the energetic flow between us.
Yet if we can learn to make use of our pain, it can be an invaluable helper and guide on the path. For it exposes and directs our attention to places inside us where we are shut down, contracted, and half-asleep. If I can move with my pain more fluidly, my rigid defenses start to dissolve and I become more permeable to love's awakening influence. And when I can let my partner see my hurt, instead of hiding it away, where it may fester and poison the relationship, this creates greater intimacy between us.
Of course, nobody wants to feel pain. Yet to become a warrior of the heart--one who is willing to risk being wounded in the service of love--we must be able to use the pain that relationship inevitably brings our way."
Letting someone see your pain is not about whining or making demands, but about being truthful and present. Welwood also says, "Awareness holds no grudge . . . it simply allows us to see what is," and that "trying to find the right way to be" (instead of just
being) keeps us from being genuinely present. It's okay not to know what to do or to be uncomfortable. It will pass, eventually. And if your wife can't be present in the face of your pain, then what is
she avoiding? Perhaps her whole involvement with OG is an avoidance of something! I found it interesting that you started off this thread by saying "Our marriage has been very happy and successful. It still is." Yet, the more you reveal, the more it seems like there are undercurrents of resentment and festering anger.
You mentioned that both you and your wife are in marriage counseling -- is that in group sessions together, or separately? I think it would behoove you to talk together in therapy about every microtruth of what's going on for you. AND ask her to register here and post her side of the story. We won't bite.