A 15-year-old boy is facing charges after his friend was brutally beaten over the head with a metal pipe. According to police, the two friends were walking along Hemingway Lane in Walden Monday night when they got into an argument. That?s when police say 16-year-old Billy Cottington picked up a two-foot long exhaust pipe and hit his friend over the head. The victim suffered severe head trauma and was flown to Westchester Medical Center. He is expected to be released Wednesday. Meanwhile, Cottington was charged with assault and is being held at the Orange County Jail.