I'm so sorry this is what is going on for you. Having chatted with you in PM's I really think at this point if she is saying you will "poison" her relationship she doesn't love you any more. Go find someone who wants to share everything with you and get out before you give her the pleasure of being the first to say its done.
Please ask her to stop saying she is poly too as its bullshit. She doesn't know what the meaning of the word is.
Anyone want to be friends on Facebook?
Send me your name via PM