So she broke agreements the two of you made and then belittled those agreements as a way of justifying her lack of respect for you? To hell with that, dude...walk on.
From here, it appears she stepped out of line and it's now up to her to make things right. She broke trust and played you false--she has a moral obligation to make it right. She can live up to her commitments or not--it's not your place to try to clean up her mess.
I find the approach of one partner trying to foist polyamory off on another without warning to be extremely rude and dishonorable. I'm not an advocate of automatically trying to adjust to a poly arrangement just because of a partner's bad behavior. Fuck all that--nobody should enter into a polyamorous tangle in that fashion!
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.