Backseat, I too had trouble letting go of the past, the pain, and that led to anxiety that kept me up all night long.
Maybe this article can help you. It's written by our very own forum host, DocJohn and is about how to let go. I followed the steps and feel completely at ease and at peace now. I hope it does the same for you.
Learning to Let Go of Past Hurts: 5 Ways to Move On | World of Psychology