Over the course of the chapters, we learn that the whole loop began because of her illness and accidental death. We also learn that Gail is actually Primrose and that Megan will thus likely choose option 3 offered in the Note from gail.
During the finale, you will need to use the Buckthorn smelling salts on her.
At the end of Desperate Times, Gail will revert to her Primrose self and reconnect with her Mother.
In Desperate Measures you will question her about the Needle to see if there is a way to stop Kerapac.