The week is up. I am writing this on the seventh day. I have not slept more than four hours in a row for any of the seven nights. I have spoken to my husband. I have spoken to my therapist. I have spoken to a nephrologist who does not know Harper, who agreed to consult with me for a fee, who explained the surgery, the recovery, the lifelong reduced kidney function, the statistical risk, the emotional implications of donating to a person you are estranged from. I have written the letter I would want Harper to write me if she were the one being asked. I have not been able to finish the letter because I keep getting to the same sentence — the one where I would need to say, "I'm sorry I told you at your birthday that you were never my sister" — and Harper has never said those words, and I have come to believe, after seven nights of not sleeping, that she is never going to say them. Even now. Even dying. The kidney she needs is in my body. The sentence I need is not in hers. And I have been trying, for seven days, to figure out whether the exchange is one I can live with.