05/22/2009 at 01:15 PM EDT
Natalie Cole was with her cancer-stricken sister Carole "Cookie" Cole when the Grammy-winning singer got the call: a donor kidney was available to save Natalie's life.
"She said, 'What do you mean? I can't deal with that right now! I'm here with my dying sister!' " Natalie's other sister, Timolin Cole, tells the New York Post
. "And they said to her, 'No, ma'am. We've got to do it now. You've got to be at Cedars-Sinai in two hours.' "
"I told her, 'Natalie, this is God's gift, and you've got to go now. Cookie would want this for you.' "
Cookie, who had been diagnosed with lung cancer just the week before, died during Natalie's surgery, Timolin said. "This is all so surreal, and it is devastating."
Natalie, who has hepatitis C and required dialysis three times a week, had a successful surgery, and is expected to go home over the weekend.
"She's doing well," Timolin tells the Post
, "and she's going to party like a rock star in no time."