Why did Fallyn kill Dory in Accused at 17?

In "Accused at 17," Fallyn kills Dory in a fit of rage after discovering that Dory had been blackmailing her. Dory's manipulation and threats push Fallyn over the edge, leading to a tragic confrontation. This act sets off a chain of events that explore themes of peer pressure, betrayal, and the consequences of impulsive decisions.