It takes a lot to make me angry, so that doesn't leave me with much that needs forgiving.
It probably helps that I'm good at detecting good-hearted people vs people that can't be trusted, so I just put up boundaries around people I don't trust, and that usually does the trick.
It's usually when I start noticing that someone seems to be deliberately trying to hurt me, over and over again, that I start getting angry. But before I get angry, first I am puzzled, and try being nice to them to see if they'll stop. Then I get frustrated if that doesn't work, and keep questioning myself whether I'm imagining it or not.
By the time I'm not questioning myself anymore and am completely frustrated with them for being such an asshole to me, without knowing what I did to deserve it, I am seething with anger bordering on hatred.
This has happened twice in my life now, both in the workplace. Neither of these people has apologized to me. Luckily, I don't have to see either of them anymore. One of them I've pretty much forgotten about, and the other I've gotten to the stage that I can usually think of him without getting angry, but not always.
I'm pretty sure I would feel a lot better if they acknowledged it and apologized to me, and might even be able to forgive them. They both seem pretty self-righteous, though.