Is it a sin to masturbate? I work as a salesman where

Is it a sin to masturbate? I work as a salesman where i travel abroad a lot, staying for weeks away from my wife. i don't like to pick whores or prostitutes, thought they are available wherever i go, because i'm a loyal husband, beside i do not want to transfer a disease to my wife. so i masturbate a lot in my hotel room please God, forgive me.