IS she being unreasonable? Or is it me?

It all started when I left our hometown for a place in the country.When I left I didn't tell her that we were leaving because #1 I knew she would tell me it was a bad idea, #2 because we did not know we were leaving until about a week before we left. I have attempted to apologize several times but she won't accept my apologies. It has been almost 3 years since that incident. She says that she doesn't want to talk to me ever again. Despite that she still sends forwarded emails and responds to mine every once in a while. If I respond to hers, she gets mad writes mean things to me. she remains in close contact with my mom and even has invited my mom to go live with her on more than one occasion. I am confused because she is sending mixed messages. we have been friends for more than half of our lives and am saddened that she wants to throw our many years of friendship away. What should I do? Should I just write her off as a friend or should I be patient and wait for her to come around?