How do you get over severe mental and emotional trauma ?

When you can’t/don’t want to let go, and you can’t accept everything that has happened ? Physically abused, mental, emotional, and financial. How can you let it all go and leave it in the past? How can you forgive the person who did so many horrible things to you? How can you forgive yourself and not feel like you deserved it, and it was because of your own fault this happened to you ?