What method have you used? Are you sure it is being seen or heard? For example my old email got blocked. Had to get a new one. Then I lost my phone so had to get a new one and number. However If you are sure they have seen and heard all that you can possibly say, it is in your best interest to walk away. The pain can never cease until you do. Plus, should the space renew both of your resolve, they could reach out and it could be a happily ever after. (That's my dream and I'm sticking to it lol.)
The only thing we have control over is our emotions/reactions - the past we cannot control, no matter how many times we replay where we went wrong. For what it's worth, I don't think friendship ever ends, simply is just put on hold until you next meet...