"Timing", its pretty hard to swallow
I am sorry to hear about your situation. I have been there. Actually, I have been on both sides, her's and your's and well his too...
People exist in their own time... the way we develop, the way we learn, the way we understand. It can be a wonderful thing when two people meet who just happen to be in the same place and time in their lives. It can also be a very hard thing to deal with when two people meet who are not in the same place and time.
Your ex was not in the same place that you were when you both started dating. She still had feelings that she needed to deal with and emotions that she had not sorted out yet. It's ok, I am sure she didn't do it out of malice.
The downside is that you were ready. No matter what you do, you cannot change where another person is. They have to find their own way. I'm sorry.
The other side of this coin is that very soon you too will meet someone who thinks you set the sun and stars. She will laugh at all your jokes, and write you love letters, all the while wondering if you are the one for her...
The question you have to ask yourself is, " do you want to be ready?"
Will you be your ex, in that you will engage in a relationship before you are ready, and do to another what she has done to you?
Your relationship with this girl was a great learning experience. YES you love her, and YES she loves you... you can muddle through this, slowly, and you may even make progress. Until she deals with these other emotions, though, nothing will be solved. Unfortunately, she has to deal with these on her own.
I know this isn't what you wanted to hear. It may even make me sound like a synic. I wish you the best of luck. Just do yourself a favour, and in a few months, when you meet that beautiful girl who makes your heart speed up, and your palms sweat... stop and consider where you are... are you where you need to be, to be with her? or are you still holding on to something else...
Best wishes...
Thinker