Laura Linney couldn’t bear to watch herself on the big screen outside Donna Karan‘s Hamptons estate, where stars gathered to celebrate the launch of her new Showtime series about cancer, “The Big C.” Linney was spotted chatting with two friends outside the party during Saturday night’s Cinema Society screening. When we asked her why she wasn’t joining the likes of Gabourey Sidibe, Oliver Platt, Edie Falco, Olivia Palermo, Linda Wells, Reid Scott and John Benjamin Hickey, she said, “I have a hard time watching myself. I usually walk out and come back in.” Karan had good reason to open up her East Hampton waterfront home for the event — the superstar designer lost both a husband and a best friend to cancer. Sarah Jessica Parker, casual in flats and a tunic, worked the room with hubby Matthew Broderick. Martha Stewart slipped out during the closing credits and whispered to a friend: “It’s uncomfortable to watch, too many friends have died of cancer.” She wasn’t planning to stay late; her pooch was waiting for her in the car.