I feel for you. I would take it personally too in light of the swinging thing and the secrecy. I would be mighty confused and hurt.
I think that a vee could work no? I am the hinge of a vee and we are working just fine as a unit of three. A triad indicates sex and connection that comes with it to me. But my two guys have connection and a strong bond, that is why it works so well. I think that really its ideal and could be for you too. After all, you know your new metamour more that most would at this stage. that might be a good thing. An adjustment would have to occur though I would think... that is a hard blow to go from girlfriend to metamour.
Anyone want to be friends on Facebook?
Send me your name via PM