You could try loving-kindness meditation.

When hating someone, you could say to yourself any part, or all, of the following:

May you be safe.
May you be healthy.
May you have ease of body and mind.
May you be at peace.

In extending loving kindness to others, you may find that your own resentments and hatreds will lessen as well.

(((((LittleEarthquakes)))))