If you hate someone, hate them. Don’t be fake and pretend you’re great friends with them or go and get involved with their life. It’s okay if you go around and ignore what they say about you, or act like they don’t exist, but once you go around talking about them, wishing bad things on them, complain about what they’ve said to you; it just makes things worse. You become just as bad as them if you retaliate and let your emotions get in the way.
It’s difficult to deal with the hate, but once you ignore what they say, you’ll see how childish they are for constantly bad-mouthing you. Hating someone is enough. Don’t play that childish game of getting back at someone, just because you’re angry/sad/depressed for just that split-second.