Su Yin's past was something Shi Feiyang had seen in the original story, and with some embellishment, he had implanted it into Blood Rock Hermit's mind. At that time, a massive number of demons influenced his consciousness, with wild thoughts flying about. Engaged in swordfighting with others, he had no time to discern true from false, only believing it to be knowledge from his past.
He cursed Su Yin, cursed You Tan, cursed Buddhism; and with the ambient Demonic Qi corrupting him and the influence of demons, as he continued cursing, Su Yin herself became genuinely enraged. She fired back, cursing Xuanyuan Dharma King to an untimely death, declaring the Five Lascivious Venerable deserved their calamities, and that Blood Rock Hermit was destined for hell.