Ladies 21+ need advice.....?

So long story short. I met a girl at work way back when we both have been burned severly in relationships. We started to date around, a guy she liked pushed her away so she and I grew closer, and decided to date exclusively. Well this guy started e-mailing her recently, and when I last talked to her she said she is confused and that she wants to see where it will go with this guy so she put me in the friends zone. I know my head is still spinning too. Any advice, or am I screwed. The thing that bothers me the most is how a person can go from hot to cold just like that. I really felt like her feelings for me where very genuine but I'm not sure. We used to talk for hours spend a lot of time together, there sparks.What are your thoughts ladies, I need a womans opinion and I need detail. I am a guy so explain in detail. Be extremely truthful, my feelings have already been crushed so I don't think theres much left to crush. Thanks in advance.