look very carefully at your cases, I've seen them blown not as bad as yours and crack the cases, a peice of piston gets in between the crank and cases and causes it to crack. as for the debate, should you split it or not, keep in mind this old saying "you can pay me now or later" and you will pay maybe even destroying your new piston.
Also, if the clutch was slipping that bad that it wouldn't go, that could have been the partial cause of your failure, a slipping clutch generates a tremendous amount of heat, coupled with a leaking water pump seal (=no coolant). yah upon reflection you more than likely caused this destruction yourself, why in the world would you not fix a failed water pump seal? water in the bearings is never a good deal.
At any rate I hope you get by with a minimal amount of failed parts.
Good luck