Why are you asking in here? There's only really IamZack, and I'm not sure she'd say what you want to hear.
Just talk to her, tell her you felt ignored and more than a bit humiliated by her completely blanking you for her ex, you never know, she might listen and understand your feelings, and, if she doesn't, then at least you can both break up knowing why.
She might call you possessive, but it's not so much a matter of owning her as her not respecting your partnership in a way that makes you comfortable. That's not a fault on her part, or yours, just an incompatibility, it can be worked around if you are determined, or you can quit while you are ahead.