She exploded that the timing of my letter was the ultimate in selfishness and asked me not to contact her until she reached out to me.
Sounds to me as though she wanted this so badly and waited. Since it never came she decided she wanted out. When it did come in response to her leaving she felt that it was too cruel a trick of fate. She probably felt confused and so asked for you not to contact her until she was ready.
I have many women friends who have done similar things.