From my experience she wants to sort things out in her head and doesn't feel it helpful for anyone to help her with that.
I have had a similar email conversation going back and forth with my ex.
I have had a very deep relationship unravel on me and went through a similar situation so I can understand some of the feelings you are going through. I been there. It was also my first and never felt anything like it before.
It took some time, a couple of months (I just couldn't get over her), but in my case she cared so much about me that she gave me a chance to have a deep involved discussion and I understood where I went wrong and I had to make a choice.
It was clear that either I choose to understand and chalk it up as education in relationships and choose to have her help me and stay friends (we are so close best friends that I still tell her things I wouldn't tell my mother if she was still alive) or I choose to keep entertaining the notion that its not over and refuse her help in which case she would never talk to me ever again.
Belieave me when I say that when you are as close to a girl as I was, and virtually still am, that it will hurt a lot and you will cry yourself to sleep on many nights and will think about suicide and how you will never have anyone like her again.
You will never be able to reach the same level of intimacy and to be so in tune with another girl in your life if you refuse to get over it.
It won't happen overnight but it must happen. Do not be afraid to let go and try to make the best of your relationship that you can.
If you were ever truly as close to her as you let on then it's very possible that you two can still be best of friends and can share a LOT togeather if you let it.
Someday someone else will come along and you will have the confidence and education of your past experience to make the best of that relationship.
I know it hurts and I know you feel betrayed. I was in a similar situation with a close friend (just to make it feel worse). It hurt me for over six months and one of my friends was in a similar situation with his first GF and was hurting for two month.
The only thing that helped me was that I let her help me out of it and after I realized that we are still best of friends and that I could tell her anything in the world our bonds of trust was renewed.
Today I trust my best friend more than anyone on this planet.
I hope my own experience helped to understand your situation a little better.