And then the Windows failed – and then I could not see to see – (lines 15-16)
This is the final moment, the actual point of death. The speaker’s eyes close ("the Windows failed") and then all sight is gone. Even the idea of sight has been wiped away. Since this is all happening in the past, our speaker must be somewhere beyond sight. She is a ghost, speaking to us from the darkness. She has told us the story of her last moments on earth, and now she leaves us in the dark too, with just a last mysterious image.