Your past is a collection of experiences that happened. They had a beginning and an end.
It is natural to want to revise our histories to support our current assessment of the world, to match our opinions and feelings, we can't actually change our past. We can only change our relationship to it.
For example, Jamie was hit by her mother as a child. Jamie still seeks a relationship with her mother as an adult. Jamie learns that during the time she was hitting Jamie, she had lost her job, worried about losing their home and began drinking heavily. Jamie tries to dismiss her painfulness around being hit, but it doesn't work. Jamie tries to justify her mom's actions as being pushed to the brink, maybe being out-of-her-mind drunk when she hit her daughter. Jamie still feels anger and sadness around this.
But what if we found a way to hold the past and a new perspective? What if Jamie can learn that her mother was under a lot of pressure and during that time made some awful choices, including hitting her children, and that of course it was hurtful AND that Jamie was able to find ways to cope through friends and excelling at school, and learning better ways to express her own frustrations. What if Jamie could use the story of childhood abuse to reinforce her values and actions in the future with her own loved ones?
In this way, Jamie doesn't have to change the past, forgive and forget, nor does she have to hold tightly to the what happened. She can see if for what it was, accept that it was unacceptable, and realize how it has not only impacted her negatively. Instead, she has chosen to use her experiences of surviving the past to craft core values that, when lived by, create a safe and happy home for herself and her children.
The past will never be different, but every day we have an opportunity to change our relationship with the past to embolden our present and future choices and actions.