You said that you loved me, you swore that you loved me, and I believed. Now I know is was a lie... She said she wasn't cheating but talking to your ex-boy friend about what was once our relationship I think is really wrong. Him saying that he loves you and you calling him pet names is enough for me to know some thing is wrong.
Do you know the reason they broke up in the first place?
Also, how much time had passed before you and she started dating and for how long have you been with her? Is there any reason not to trust that her intentions are purely nostalgic?
You may be distorting facts to prove yourself right. It is easy to find proof of terrible news when you look for it.
My advice:
Keep an open mind and hold on to some semblance of perspective. It may not be as dire as you think.
In fact, it probably isn't. If she had some grand conspiracy to leave you and join with him again, you wouldn't even know the things you've listed. Us girls are sneaky like that. When we have a change of heart, no one knows until we are sure of what we feel and we're ready to announce the news.
Unless, of course, she is a scandalous woman of loose morals... which I doubt, even though I do not know her from Eve.