Ghost in the Machine
Depending on how well she knows you personally, you may be able to use this to your advantage. If everything she knows about you is from second-hand experience, you can call her out for assuming too much and joke around with her for a bit on it. For example, in your case:
Her: "I hear you're a player"
You: "Do you believe everything that you hear?"
You: "Then why should you believe that?"
Her: "Because I've heard it from my friends"
You: "Look, I need a woman who is able to form her own beliefs and opinions, and it seems like that you can't do that, so I regret to inform you that I will be moving on."
See how that went? You directly challenged her assumptions and put her on the defensive. While she was aiming to try and take you down a notch, she did the exact opposite. You should always try and aim to bring the game under YOUR control.
Emotions is man's number one problem. It is the mother of all bitches, because it is what causes failure. Those who are truly successful know how to keep the emotion separate from this. I do still have feelings for the girls I have had oneitis for, but it never affects me because my Mindset and beliefs have forced them onto the back burner.
Here's one thing that helped me with oneitis: dumping the ranking scale. This stupid ranking scale that I see all the time may aim to dehumanize women more, but I've noticed that a majority of amateurs who are attached to a certain woman rank them pretty high on the scale. I do not see dimes, pennies, nickles, or even pesos. All I see are sexy and not sexy. Out of the sexy group, I pick women who have at least one of my physical preferences. For example, my preferences are red hair, pale skin, short hair (even to near bald depending on my attraction), wavy hair, looks nice in glasses, or has a nice butt. If a girl has any one of these physical qualifiers, they are game for me. Forget the notion that this woman is a 9 and just consider her like you consider the rest of the women in your category: beautiful and nothing else at the moment. Doing this puts her in the flow, and when she goes into the flow, she becomes virtually nothing.
Another way to cure your severe attraction to her is to keep in mind that there are more women out there. You may think this girl is amazing and the greatest thing in the world, but when she dumps you and moves on to do the same things that you did with her with another man, when is the next time you are going to say those words? I can guarantee you that if things don't go through with her, she won't be the last person you label so highly. There are 6,973,738,433 people in this world, and when you say one in a million, that means that there are approximately 6,973.7 women out there just like her, give or take a spleen. If you say one in a billion, there's still other women out there like her. You get my drift though: She's not the only one for you.
I'm not telling you to back off on her and go on to someone else. By eliminating your emotional attachment to her, you become more natural, fluid, able to calculate without emotions getting in the way. We all have our occasional oneitis fixes. It happens. It's when we conquer it that it all becomes fun and business for us.
"There is no better than adversity. Every defeat, every heartbreak, every loss, contains its own seed, its own lesson on how to improve your performance the next time." - Malcolm X