Maybe if you "arm yourself" with knowledge, as they say, you'll lose some of that fear. I can totally relate, and I try to tell myself that I'll only gain all that back if I slip into my old habits. Think about it, you didn't get that way by eating healthy and staying active. You WON'T get that way by eating healthy and staying active.
See if there are any nutrition classes available. I know some YMCAs do them, and my gym does them. And

again.