I wouldn't worry about forgiving others unless the past problem still gnaws at you. Like if it keeps you awake at night or causes ulcers or whatever. Then you might look into a few alternatives.
Some things should be impossible to forgive (an adult sexually abusing a child, for instance) but the child, whether still young or grown up still has to live with the fact that bad things happened. But to let that level of harm continue to cause problems means that the molester is still winning. So while I sincerely hope that your past issues are not quite as horrendous, nonetheless, if you can find a way to stop it from being an issue in your current life, then you get to come out the victor.
So in essence, you're not forgiving the other person, you are figuring out a way to let their transgressions to become non-issues in your current life.
There is a cute little trick where you can fool your brain into confusing one bad memory with one good memory and after that, the bad one doesn't bother you any more. However, the good one isn't good any more either. I forget what its called, but it is something I learned back when I was willing to pay $1000 for Neuro-Linguistic Programming seminars. Which is also where I learned never to pay $1000 for a seminar again. But I'll try to track down instructions on how its done. They make it all mysterious, but it is really pretty simple. With only one lesson from the otherwise big-time rip-off artists, I actually helped a friend who had just been in an nearly fatal accident stop being afraid to drive again. I used the word "actually" there because I seldom actually succeed at anything, so it still surprises me that it worked, even 30 years later.
P.S. You will notice that Nam is so insistent on being an asshole that he won't even let you compliment him. He's good. We've learned to live with it. Hope you can too.