The worst part of breaking up is thinking of what you could have said, that final comeback that would land the killer blow. to utter it you would need to reconnect and therefore break the number one rule of breakups, being the first to say something.
I’ve been in the situation where a friendship has collapsed and finished with a “have a good life” while being, what I felt, was the injured party. Every so often I wish I’d said what I’d felt or just took a pot shot. It may have made me feel better at the time but would it have sat as well over time?