INTERVIEW-Colombian rebel deserter pessimistic over peace
Rebel doubts FARC unity inside Colombia
Rank-and-file rebels worry about future
Says commanders mistreat FARC fighters
By Helen Murphy and Luis Jaime Acosta
BOGOTA, Feb 21 (Reuters) - FARC guerrilla fighters hiding out in Colombia's jungles are pessimistic about peace talks in Cuba and increasingly afraid for their future, according to a rebel commander who has just turned himself in.