It doesn't sound like she dumped you. It sounds like she simply ended the relationship when she had to move.
There is a big difference between a break-up and being dumped!! Getting dumped is usually abrupt and out of the blue, a surprise, or a big turn-around in someone's behavior. She didn't appear to me to have dumped you because it sounds like you all discussed her situation and she chose to leave and do what felt right for her at the time. She told you that she loved you and even tried to conduct the relationship with you long-distance after she moved away. All that sounds very considerate and loving on her part! Obviously, it was a painful decision she had to make.
Instead of moving on and wishing her well, you took it personally as a hurtful thing, and now you see it as being dumped and have convinced yourself that she hurt you. But you have chosen to feel hurt, in actuality. If you had been thinking more of what she wanted and needed back then, you wouldn't have begged her to stay, but tried to find a way to be supportive and loving. I had a bf that I loved, years ago, and when he considered moving far away, I encouraged him to do it because I knew that that would make him happy, even though I would miss him. Why didn't it work out when it was a LDR?
You may want to look at this attitude, and check to see where you are being very focused on yourself/yourselves and what you are getting out of it, versus wanting everyone to be happy, and finding ways to be loving, giving, and supportive equally to each other. Just because you were a couple first, and she came to be involved with you later does not mean that her role is to satisfy the two of you. She has her own needs and wants and right to be satisfied. So, I would say that if she wants to talk about what happened, listen to her. If she wants to rekindle things with you, consider it. But talk, talk, talk, and try not to be selfish or indulge in the idea that she "hurt" you in the past - the past is past, so what do you all want now?
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein