Rhino,
Unfortunately it is a hard fact of life and no one tells you that yes, this is how almost all women operate. At least the attractive ones who have options, anyway. You'll hear the standard "her interest died slowly over months while you didn't know and she already finished grieving the relationship". And it's true.
I'm about 5 months out now from my breakup and things are finally really starting to get significantly better for me. We were together 3 years and lived together too, so I understand some of the dependency and attachment that goes on there. But I can tell you from experience the one thing that has helped me move on more than anything else:
Realizing that you don't deserve to be treated the way that you were. That you truly must knock her down from that pedestal in your mind once and for all, and acknowledge that she is not "the one". You must demand more from a relationship partner, despite your history together. I know firsthand how hard it is to walk away from that stuff. Some of my memories with my ex are the happiest moments of my life. But you know what, it's not like those memories disappear just because the relationship dies. You have to do what's healthy for you now (NO CONTACT) and then when there is a safer emotional distance, you're more free to appreciate the good times while still realizing that it wasn't meant to last.
Many of the best things in life are transitory. Accept this on a deep fundamental level, and you are on your way to enjoying life to its fullest without experiencing much of the fear or pain associated with loss.
And finally, no, she is not "replacing" you. Nobody can ever be replaced, we are far too complex to fit simple roles like that. She will always remember you for you, and you cannot try and psychoanalyze what she does now as though you're just a cog in the machine. People always think that because of the way things turn out, that it taints the entirety of the experience, but I don't believe that to be true at all. What you had together was real, it just doesn't exist anymore. Cut her loose and move on... believe me, when this is over, you'll be improved as a person in many ways and ready to tackle the next chapter.
