Aphrodisiacs help a lot. Stay out of her slime as much as you can, but if you get pulled further into it, you'll want use Distract in the case you find yourself in a bad spot or charmed, since Teleport will fizzle from her slimy (pun intended) shenaniganery. If you got the Demon Layer from donating to the church, I'd recommend using it for your damage (iirc she's weak to Holy, but if not, I find it's a really good damage dealer for most fights with only one enemy). Of course, there's always some Nightmare Labyrinth Exploration for level grinding if you feel like you are underpowered. If you don't have the Heroic Cum-back perk, I'd get it for the potential final spirit saves. Hope this helps!