I'm having the same problem. This has got to be a bug of some sort.
I have around 876 hitpoints but she damages me for 890 and I die in a single hit. I absolutely cannot seem to avoid it.
This isn't just difficult...it's downright unfair. I don't mind hard enemies, but this goes well beyond anything in the game so far. It doesn't make sense.
Unless there is a specific trick or strategy that I missed somewhere to beat her, I don't know how I'd ever win this fight.
