My take on it is that instead of her life flashing before her eyes in the moments before she dies, she herself becomes the angel and for a few seconds, which for her are time dilated into much longer, she does a good deed before coming back to her time of death.
I was a bit disappointed by the ending. After seeing her apparently save the other girl in that other accident, I had a hope that the main character too would be saved in some way. So, it was disappointing that she died anyway.
Also, I found the 2nd person narrative very frustrating. Not because it was 2nd person, but because the narrator kept calling me Abigale

. That yanked me out of the story every time.