In my experience, there are two types of breakups that are the hardest to recover from: one with a narcissist and another with an avoidant.
While these two types of people are not exactly alike, they do tend to have overlaps and the results of the breakup with either of them is often more traumatic than your average end-of-relationship experience.
I’ve had the fortune (or should I say misfortune) of encountering both types of people and while I generally believe narcissists have a special place in hell, my experience with the avoidant was way more traumatic and excruciating than that of the narcissist.