If she's a true friend, I don't think this means you've lost her! She probably is upset because she does care, she does want you to be well, and she does want there to be trust and openness in your relationship.
If you do better being more open in emails, that's OK....I am much more comfortable writing than I am talking and can express my deeper emotions to my friends better in emails than face to face. Although there's no discounting the deep value in face to face communication!
I understand about it being hard to rely on others, wanting to be self-reliant......but having good friends, even just a few, that I know I can rely on actually helps me be stronger, I think!
Give yourself and your friend a little time and the emotions will begin to settle! Be gentle with yourself.....