It's hard to believe isn't it, the actions of others and with what they stand to lose, how they still make the decisions that they do. That in itself is a huge thing to get ones head around. I know I struggle with it and go back and forth and round in circles trying to make sense of it all. Grief and loss are so hard.
You have well and truly taken all the responsibility you need to, you have done so much valuable reflection and now that you are aware of your past and how it impacts you, you will be in a much better position going forward to build a better relationship with yourself and others. You can definitely forgive yourself now and let it go.