Here are a few questions to answer:

1) This healing stills is not the last one, but Dong Fangbubai was put down behind a cliff and went to Huashan Mountain (where Ling Huchong studied the Nine Swords of Dugu) in a daze, where he met the breeze. At that time, the breeze helped her treat her internal injuries (this is the origin of healing stills).

2) At the finale, Dong Fangbubai and Ren Yingying (Ren Yingying and Ling Huchong don't know, only Pingyi knows) changed their minds, and then Pingyi threw Dong Fangbubai into the cold lake after the operation, which means she was "dead" in the plot. But this is not certain, because in the last picture, Dong Fangbubai under the ice lake is listening to Ling Huchong & after Ren Yingying's speech, she suddenly opened her eyes, which may mean that she is not dead, but healing in the lake (or delaying the toxic attack or suffering from poison alone).