5. In Rt $\triangle A B C$, it is known that $A C=6$, point $E$ is on side $A C$, satisfying $C E=2 A E, D$ is the midpoint of the hypotenuse $A B$, $F$ is a moving point on segment $B C$, satisfying $\angle E D F=$ $90^{\circ}$. Then the maximum value of $B F-F C$ is ( ).
(A) $2 \sqrt{2}$
(B) $2 \sqrt{3}$
(C) $3 \sqrt{2}$
(D) $3 \sqrt{3}$