[Altima of the Gates]

Spoiler for HF:

Well I don't think she knew persay (given that her memory of that would be fuzzy at best, given that she was hallucinating in a dream-like plus getting Gate of Babyl'owned I think she had more on her mind other than "hey I can regenerate'.), it was just either be possessed, or rip him out, so she ripped him out. Consequences be damned, he just had to go. Though amusingly, she did muse on the fact that had Kotomine not gotten rid of the other worms she would not have had enough control to pull it out of her heart.