First of all, she has absolutely no reason to trust him at all. Second, after the decapitation video, why would she ever trust a video in favor of their captors as evidence of anything. Third, he said it himself, the plan failed.
Honestly, not a fan of how Conia kinda took over the series. Was fun for a while but it keeps going with the other two sisters barely getting a word in.
Yeah, not sorry for her at this point in her life. She went from defending herself to eating humans indiscriminately. Unprompted she pursue the party and tried to literally steal a bite out of them.