I'm having a bad past and it was not easy to forgive and forget. I've already tried my best to forgive people, but I still can't find the inner peace. I still can't find what I should be. Why it is so hard to forgive people? And why it is hard for me to forget the past. What should I do?
You are a human living in a human body. It is a natural part of you to find it difficult to forgive people who have injured you, since the subconscious part of the mind keeps track of every harm others have done us and in this way controls our emotions toward them. This is done for our own good, it is an automatic response meant to help us stay away from people who may harm us.
It is sufficient for you to consciously forgive people (to decide in your mind to not try to harm them or take revenge on them), as for your subconscious mind, it will continue to have its negative emotional response toward these people until a long time passes and you either start to see these people in a new light based on positive interactions, or so much time passes that you forget most of the injuries they have done you.
If you can consciously forgive people, and you can control your actions toward them, then there is no need to worry about the rest. Your focus should instead be on maintaining a heightened state of spirituality (through daily Quran reading, listening to lectures, and other acts of worship), increasing your knowledge, and always going closer toward God. As you improve in these regards, the worldly things that trouble you will feel less important.
Your subconscious (the emotions you feel toward people) is not under your direct control. The only way you can affect it is indirectly, by focusing on things that can rewire its priorities so that it stops worrying about people. And this is done, as I said, through days, months and years of spiritual practice.
There were people in my life who were extremely unkind to me years ago. Instead of trying to forgive them, I moved on with my life. I read hundreds of books, traveled, suffered many hardships and many good things, and in this way the negative things I felt toward these people became irrelevant, so that today I can interact with them without feeling anything negative toward them.
This is similar to how we do not feel strong emotions toward people who were mean to us in kindergarten or elementary school. It is not that we actively forgave them, it is that we grew up, we changed, so that they no longer feel relevant to us, to our emotions and our sense of self-worth.
In the same way, to forgive someone, a person can go to a different country, spend 5 years there and become a completely different person, and coming back to their home country, they may discover that they have forgiven the person even though they almost never thought about them.
To forgive, grow into a new person, move to a new position in life where those people’s negative actions toward you no longer feel important or interesting, so that you do not even bother to think about them anymore.
Besides Islamic worship, another thing you can do is to read 100 books. Read 100 good novels (classics written before 1965) and I guarantee that you will feel like a very different person once you are done, your view of yourself and the world around you will expand and you will start to see the world differently, so that your past stops having the power to hurt you.