Sucks dude. Same shit happened to me. Together for 6 years and the seperation anxiety really kicked in after college when she had the freedom to leave. She had the homesickness as soon as she hit college (we met a year and a half into college). In my case there were other things that caused the end like lack of a ring after 6 years and whatnot, but the homesickness was the main catalyst.
I say if you were happy with her, try to get her back. What you do not want to do is follow her because then she absolutely has the sack under lock and key. And all these dudes here act hard, but they are probably lonely as hell anyway.