I think that one of the hardest problems we have as members of the human race is this; when we hate someone, it's extremely difficult for us to move through life when no one else feels the same way about the person we hate, or, even worse, when those we love still like that person, or when the depth of their condemnation for the person seems to lack the degree appropriate - the degree demanded by our fiery burning hate. It's marginally harder - even for those of us practiced at the process - to hate someone without help. It's not vindication we need, though we feed on that when it happens, it's just about empathy.
When Bastard X (who for the sake of argument we'll call Bastard X) has wronged us, we want to have people we love around us so that we can run to them and tell it on the mountain that Bastard X is a bastard. And to have them agree with us? There is nothing so euphorically vindicating than to have Friend Y wholeheartedly agree with us about Bastard X's bastardness. We need to vent, to commiserate, indeed, the only things Misery might love more than Company are Sympathy and Affirmation. Misery probably loves Company simply because Company can provide those qualities in greater degree than anyone else.
The point is this: Whatever Bastard X does to us directly is so big that we fail to see any other qualities in him/her/them for a time. And it could be a long time. And unless whatever Bastard X did is so objectively bad that it brings EVERYONE around (and it never is, even fucking Hitler had friends) there's always going to be someone you're talking to who doesn't get why you hate the guy who they have class / drinks / church / sexy times with. They can't see it, while to you, it blots out the sun. Sometimes they're obligated to get along and won't allow themselves to see it, or they're on personal journeys and shit. That's always the worst.
Other people's hate touches us all the time: parents get divorced, and unless one of them is an objective prick, you usually have to get along with them both. Couples split up and one half of them will vent to you about what a psycho the other half is and then say shit they don't mean like, "I know you guys are still friends, so I'm cool with you hanging out with her still," when what they really want YOU to say is, "That bitch." Friends bail on friends, co-workers stab one another in the back, shit happens all around and these people forget that you're not really in on their drama at all. It'll happen to you if it hasn't already - someone will wrong you, and your intimates will continue to get along with that person, and indeed, find value in their character and person. And it'll hurt.
Secretly and close away near the hearts of the person (subjectively) wronged is often the dual suspicion that Bastard X is quietly and objectively one of Shakespeare's smiling villains and that Bastard X will slip up eventually and reveal what a fucking bastard he/she is to everyone else. And then they'll see. Oh, they'll all see it then. They'll understand that you were not, in fact, just a virulent sack of hatred and poison all this time, but a prescient and insightful judge of character, way ahead of the curve.
What I'm saying is; It's hard, hating someone who is really deserving of hate, and it's not like anyone's going to help you - you're on your own. If they're really, really terrible, though - just an absolute shit of a human being - you'll reach a transcendent, white electricity point of hate, and it will become light and easy to carry. And if they're really as bad as all that, well - it's usually worth it, whether you can share it with anyone or not.