Juana wants to get rid of the pearl, but Kino refuses, and tells her, "I am a man". What does he mean by this? Is she right to be afraid?

Kino is obsessed with the pearl, and although Juana will do whatever she can to rid them if its evil, Kino remains the head of the household.

At this point in the story, Juana has every reason to be afraid. Kino isn't thinking about her or his son.... he's thinking about the pearl and what he believes it will mean to them.