Her surgeon will tell you the news while she's in recovery, handing you, Gillian, and Zoe literature to read. "She has glioblastoma multiforme," he'll say. Something in the glial cells in her brain went horribly wrong, developing into a rapidly growing and aggressive cancer. He'll tell you that they went ahead with the implanted chemotherapy, and that they'll likely be recommending some combination of systemic chemotherapy and radiation after the final report is in.
He'll tell you that they've removed as much of the tumour as they could have without permanently disabling her, but that's not a cure. He'll tell you (though you'll already know, because this is the worst case scenario you scared yourself researching) that her condition is ultimately incurable.
Zoe will ask how long she has. He'll explain that while every case is different, she's probably looking at around a year, that it wouldn't be unheard of for her to make it two or three years depending on how she responds to treatment. He'll recommend against being too optimistic, to wait and see.
Your whole world will fall apart.
Emily will have another seizure during recovery. You'll feel so helpless, so tired. You'll pray to things you don't even believe exist that you could just take her place.