So that we update ourselves with the principles of justice that normally govern.. What is legal and illegal in the normative context of each community of individuals is one thing, and what seems to be right or wrong for each one is quite another. But as luckily we no longer live in the times of the law of retaliation, also luckily or (at least I) no longer live under the justice preferences of any mafia sect. So it depends from what type of ethics you see the issue, the matter changes. But I think that constitutionally in all modern societies/states things are quite similar and rational.
As for forgiving relative things, or that kind of thing that at least is not under the law in a subjunctive and direct way, it is quite complicated. Sometimes not everything can turn out the way you want it, sometimes people are not what we think is right for them to be or in the future you may see that the majority will almost never act in the way that seems most consistent with your referential system of beliefs. Sometimes it's hard to pass off these different actions or forms because they're things our inner consciousness of fairness has to deal with, especially if your personality tends to be sensitive, dreamy, or idealistic. Reality very rarely has to do with those, inner fantasies. You can't even be exempt from people lying to you, even if you are the most honest person in the world. You will always be exposed to being cheated, lied to, and almost all the "evils" in the world. It is up to one to be carried away by these social traps or not. To forgive, well, for me, to give an example, at one time it was very difficult for me to forgive certain relatives who criticized me in some way and said that I was crazy. What a big thing that was in my adolescence, making me so much deep noise. The truth is that I couldn't do much to change them, I couldn't understand them either, and what did I have to forgive them for? what were different? Over time you learn to ignore things you don't like. That's what I learned. And I also learned that there is no law that says that being crazy should be punished (which I am, come on, I always was) or that criticizing someone who is crazy should also be punished. Taking things to the extreme of due ethical limits if it is out of place, for example. Such a, killing a crazy person, stealing, or that kind of thing that almost everyone knows about. But in general one has to learn to tolerate the difference and let it go.