Life is too short, sometimes complicated, messed up, there are too many things to take care of, too many interesting and some more interesting people to deal with. At the same time when we are surrounded with this negativity, we have to devote time, energy, and passion to make great things happen, create the means to make our lives fuller, richer, raise a beautiful next generation, and also make better humans and souls out of ourselves. How then do some of us get the time and energy to hate anyone? Hatred is useless. It not only makes zero difference to the object of our hate but it also causes us to expend our energies which could have been otherwise spent in doing something good.
It is okay if you can't spread love and kindness, but don't spread hatred and don't waste your life hating anyone or hold grudges against anyone for too long. Live with a light heart and free spirit - who knows if you'll get to see tomorrow?
It is true and correct too, that sometimes we have to act stern and protect ourselves. But there are times (more often than otherwise) when we need to understand that reacting strongly is not always necessary, that we have to accept that hatred as another penance we had to pay in this lifetime, and let go and move on.