MATAGORTA BAY, Matagorda County - For hours after their boat sank, Ken Henderson and Ed Coen treaded water in the Gulf of Mexico, talking about life and death while struggling to survive. For more than 30 hours, it worked. Then Henderson was forced to make a decision that would save his life, but not his best friend's. "This is the last-ditch effort, but I'm going to go for help or you're not going to make it," Henderson told Coen, just before cutting the strap that connected them in the deep, cold waters off the Texas coast. "I understand," Coen responded,...