Check out rumination-focused cognitive behavioral therapy, ideally with guidance and support from a therapist. I used to hear "just let it go" and think I was

Check out rumination-focused cognitive behavioral therapy, ideally with guidance and support from a therapist. I used to hear "just let it go" and think I was being asked to do something impossible! Using a third arm is a great way of putting it. Turns out the self-regulation needed to "move on" is just a developmental skill. Like any skill, it can be practiced and improved over time. Hope you find this encouraging!