when those thoughts arise, when flashbacks trouble you, try this;
"I am grateful these images are not ME. I am grateful for the ME that I AM. I forgive myself for those events behind me, when I did not honor ME...."
Or anything along those lines.
The point is to acknowledge;
1 - our past is not who we ARE
2 - who we are NOW is not that person
3 - It is ok to forgive ourselves and move on
It will get better with time and self-kindness