Pieanne, That sentence, "I met him five years ago" could indicate that you still know him, or that you have known him on and off for five years, as in:-
Question:- "Do you know him?"
Answer:- "Yes, I met him five years ago."
A better answer would be "Yes, I have known him for five years." (But you can never control what people are going to say).
An answer of, "I met him five years ago," is ambiguous and would prompt me to ask for clarification, "Do you know him well? Do you still know him?" (Especially if I were a roving reporter, or I wanted a reference for him).
Then the clarification could be, "No, I only met him once at a party".
or
"Yes, he married my sister."