I am going to post as if I am an expert on the topic, not that I am. I won't say "probably" much--just "this is how it is". I am teh forum multi-expert!
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If she's going to be that much trouble, forget her. You've had 3 years and have probably continued dating--mark it old news.
Women are always difficult, but if that is her personality ask yourself if you want to continually put up with it...because I doubt she'll stop.
Overall, this is how it is vs. how she sees it (exaggerated, but probably a 50-75% of being accurate):
HOW IT IS
You had to move (not your decision) and gave a (presumably) sad farewell. Now you're at the same establishment and have a chance to regain an old friend.
HOW SHE SEES IT
You and you alone entirely made the decision to get away from her, probably because of something you saw in her you didn't like. Now you're back and want to pretend like you didn't move because of that.
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