Use runes and accessories that increase the amount of exp you gain and level defensive stats (willpower, allure) that is if you're playing on easy otherwise I dunno lel
Another way, is to use manticore spikes. I think I used around 10? Also I was level 50 when I fought her, it's been awhile though so I don't remember what skills and perks I have.
She's weak to aphrodisiacs', and they can stack. Use items or skills that focus on that, it's usually how I beat her. Need to have willpower fairly high too, because you do NOT want to be 100% slimed with her