how can I best explain the "fear" involved in winston

The best way to show Winston's fear is to put it in perspective with his lonliness. He's very lonely and meets Julia who becomes important to him and eases that lonliness. But, when he and Julia are caught and Winston is tortured with the rat (the one thing which he fears the most). What does he do? He says one of the most chilling lines in literature: DO IT TO JULIA. He loves Julia and she's eased his lonliness and has helped him feel so much. Yet, facing the worst fear imaginable to himself, he doesn't just scream--don't do this to me. He screams to do this horrible thing to her.

Therefore his lonliness means less to him than his fear. And that is the point of 1984: if you know what people fear, you can control them because fear is a driving emotion. Fear beats out everything else and how a society like the one which Orwell describes can function.

"Do it to Julia" is a quote commonly used to convey the complete isolation of the human spirit when faced with overwhelming fear. When the Nazis were going door-to-door and looking for 'undesirables' and a neighbor pointed at the door of another-- basically turning them in? They were doing it to Julia. When humans reach this point of fear there are no societal obligations, no caring of others, no Golden Rule: merely individuals creating their own lonliness which they choose over fear.