the actor , 61 , appeared on good morning america to promote the forger .
was asked about controversial scientology documentary going clear .
film alleges church elders hold a ` blackmail file ' to keep travolta with them .
travolta insists he has ` loved every minute ' , it is ` misunderstood ' and it has helped him get through hard times over 40 years .
tells his critics to ` read a book ' and not to ` speculate '