We live in a time when people set out to have no enemies and, in so doing, heap up enemies in every place they wade around, often creating them out of their own friends. On the other hand, they may go looking for them, convinced by the modern maxim that if they don't have enemies, they're not doing something right.
As if there wasn't a balance; as if one could measure one's worth by how much imbalance one creates.
An enemy is, ultimately, someone who is both unwilling to compromise or who puts you in a position where you are unable to compromise. There may be hundreds of reasons for this lack of compromise. There are situations in which one shouldn't compromise, thus causing one to create enemies necessarily.
Beyond that, there's not much else you can say about an enemy. There's no rule book. There's no one standing over you demanding that you have to strike your enemy down or forgive your enemy. It is ultimately up to you. Not only is it up to you, but the circumstances may change quite drastically. The person you consider an enemy may decide to compromise later, or maybe you'll decide you were wrong. Maybe you'll become friends. Maybe that person will leave, or be put in prison because of their choices. Maybe you will. It's like friendship. It might not last a lifetime, but it very well could. Your relationships with people are constantly in flux.
No matter what you choose to do, however, remember that hatred doesn't help your purpose. Hatred is destracting. It is a high stimulation of the nervous system, which loops back into a sort of fevered obsession in which you start isolating that person in your mind as if to put a curse on them. You're only cursing yourself. Hatred muddies all waters and eventually becomes addictive. When you have no object of hatred, the obsession continues, even if you have to point that nervous attention inward. Hatred creates enemies as much as it perpetuates enemies.
Think about this as a freedom. You don't need to hate your enemy. Think of hatred as excess stress. It is something you're holding on to. You don't need to consider an enemy any less so because you have chosen to do away with the current of hatred. You simply understand the relationship and do what you have to do.
If you look at an enemy without hate in your heart, any number of things work to your advantage. Maybe it will cancel the aggressive nature of your relationship. However, it could also cause you to notice things the other missed, or to plan better. In any event, the point is to create harmony. Hatred never does. It only perpetuates imbalance.
Hatred destroys you from within. It becomes a fight with yourself because you didn't cultivate the strength to overcome your difficulties. Love is extroversion when it is done best. It starts with goodness from inside and puts it into the world. Hatred is introversion, as it starts with something you interpret as bad before you turn it inward and keep it locked inside of you.
Think of love for your enemy as respect. This doesn't mean letting someone harm you. It means taking the care needed to apply the appropriate way of fixing a problem on its own terms.
Anger is different. It is a feeling. Hatred is more like a commitment to keep on feeling the same. It is a commitment to self destruction, hoping that you can take the other down with you.
Go ahead and feel the anger, let it pass, and then figure out what to do next. Don't ever commit to blindness.