So Sad-show piece coral dieing

[Tangman]

I have a large Toadstool leather (sarcophyton glaucum) 18" or more across that is dieing from a bacterial infection. I am fairly sure it was from stirring up the crushed coral substrate, trying to clean it. This has happened once before after mucking with the substrate, but the infection wasn't as bad and it heeled on it's own about a week. This time though it has only gotten worse, it still has polyp extension, but I feel I may have to frag it to save it.
Any one have any suggestions?
So sad to loose such a great piece.....thought I would vent anyways