Originally Posted by EurAsianGirl
He was planning on telling her about us and the triad plan eventually, then the other girl happened and it made him think that Poly was too much trouble. Basically the other girl ruined everything, though I will admit I hated the situation at first too, I felt so guilty that I was having a relationship with a taken man, I hate those kinds of girls even though I realize saying that now is hypocritical.
OK, there is a definite issue of perspective here.
This idea of "I'll get into another relationship, then, when it works out, I will tell my current partner" - that is lying and cheating, and it a betrayal of their relationship. Expecting that she would magically accept it all and you all three would live happily ever after was a pipe-dream on his part.
This fourth girl was NOT the person who ruined it all, in my opinion - HE did, by starting the whole thing off on the basis of lying and cheating with his existing partner. That is pretty much totally opposite of what polyamory is all about. In fact, I would actually thank the fourth girl for what she did (even though her motives may have been less than pure), because this would NOT have worked out and would have caused you far more pain and effort than you are going through right now.
OK, back to the original post - you asked for advice... well, here is mine:
This will never work out with him and her. You need to walk away and get on with your life, and not spend any more energy trying to make something work that is doomed. Or you can choose to be his "bit on the side" while he lies to his main partner.