It helps to separate and to quantify. To decide that the person was/is wrong, but I won’t remain angry. Often times I look back at those who have wronged me, as a fellow actor in a play. It is now in the past.
When you define something strongly it become academic and unemotional. When you think, he was surely a Baheima for grabbing that out of my hands, you can now stop being angry at that Baheima. You can even be friendly while being careful not to allow him to repeat his prior actions. You can be friendly toward, and even love, an animal, but you won’t trust a sandwich in front of it.
There are people to whom I carry no grudge at all, although I know that they were wrong. I know not to trust their judgement, and I’m also aware of their many fine qualities.