Be grateful for having had her in your life, but also move on. You sound like you're dwelling, which is to an extent unavoidable, but its not healthy to remain at that stage for any longer than necessary. From what little I've seen of you, you seem educated and intelligent, so you hardly need me to remind you that Carl Jung defined love as essential insanity.
Such is the way it is, but eventually we have to move on. Truth is that life is volatile and people rarely remain the same for months, let alone years in their formative years.
You haven't been merely disposed of, because if nothing else, she did spend a great deal of time with you. That's that, though, and now you need to forge ahead and find happiness for yourself, just as she does. Try not to expect too much from anyone except yourself, remember that you need to be the most important person in your own life, and be forgiving of yourself.
There was something, and it has passed. There is time to mourn, and then, there is a time to end the mourning, too.
