Hello la bella vita: I'm so sorry you are carrying this burden.

There are also some things in my past that cause me sometimes unbearable sadness.

(And I have tried to put an end to my existence... multiple times...) I also know what it is like to not be able to share it with anyone. Oh, I guess I could see a therapist. But what's the point? It wouldn't change anything. What's done is done. It was all over with many years ago now.
I have an internet acquaintance who is a devout Christian. I'm not. But if I were he's the kind of deeply thoughtful Christian I would want to be. He has tried to convince me that it is possible for one to forgive oneself. However, for my part, I maintain there are some things so egregious that self-forgiveness is simply not possible. This is how I feel about myself. So, in my life, what I strive for is simple acceptance of things as they are. I don't have any suggestions or encouragement to offer you here. I simply wanted to share my experience.