Mama usually calls maybe once a day. Today she called four times. Her knee replacement surgery is next Monday. She’s concerned about her wardrobe, the low potassium diet her urologist has recommended, and the three weeks she’ll spend in post-operative re-habilitation. “Your father doesn’t want me to go to re-hab for three weeks,” she says. “He says we can do everything I need right here.” “Well, he’s wrong, and Dr. Shell wants you to go to re-hab,” I say. Dr. Shell is her orthopedic surgeon. “I know. I want to go to re-hab, too. I need to do it.” “You just want to know he’s going to be okay without you?” I ask. “Oh, he’ll be fine,” she says, waving it off. “He just…