Succinctly put — but you can leave the past behind you if you let it go — or quite a lot of it anyway. It is just a fiction, a memory, a perceptual position you or someone else once took about a sequence of events. It is not real so you can leave behind as much as you want to.
What you can’t get away from is what is inside you. You can never escape anything until you release it, your anger, your fear, your bitterness, your shame and guilt. But they are not the past they are just labels we hang on it. I have been incredibly happily married for 20 yrs now but before that not so lucky. I don’t remember that person any more though. Even the person who made her marriage vows 20 yrs ago is not the same body, not the same bones, not the same cells, not the same age, not the same thoughts, not the same experiences, not the same life paradigms.