Is it possible for you to load the savegame and "quickly" pause the game and used first your most greatest healthpotion, than quick pause the game, use than you biggest Rejuventation potion, quick pause the game and "see" if you can run a little out the way of Stone's attacks!
Then try to run whole the time and evade Stone's attacks .. and if your potions are completly taken, you can take/use back over again HP-potions (or food) ... and so on!
Try to full up you HP-bar and if you successed, quick pause the game and make a extra SAVEGAME!
Is that all not possible? I'm afraid you must play from a previous savegame
...