Complex sentence: One vivid detail that she recalls was her riding on a donkey when she saw Jerusalem for the first time and that she nearly fell off of the donkey because she was in such shock from the vision in front of her.
Split into simpler sentences: One vivid detail that she recalls was her riding on a donkey when she saw Jerusalem for the first time. In fact, Kempe brings in the detail that she nearly fell off of the donkey because she was in such shock from the vision in front of her.