Should we forgive our enemies?

We have to. And you will never understand until you are put in some situation where you must do so or sit in your own hate forever.  

We should not afraid to if it is worth!

That whole thing is totally up to you.

It would depend on how badly that enemy has hurt me.  

This is subjective to each person and each case. 

No...you end up with no enemies.

After you have healed sufficiently from the harm that they caused you, forgiving them is probably the best way to set yourself to move forward---just don't forgive them to soon.

And of course, you don't have to like them to forgive them. 

Hatred destroys the hater not the hated, you have to find someway to untie yourself from that person for your own release and freedom.  Hatred ties you to the hated and eats you up, and if not dealt with becomes heavy baggage and possibly illness.

No ... forgiveness vs hatred are not the only choices.
I have people who have wronged me ... thus you could call them my "enemies".
If they do not ask forgiveness, I do not give it.
But neither do I dwell on it (hatred).
I just continue living my life.
Eventually, I may even forget.