you could also do it somewhere close to the ending, or you could make a chapter that focuses on this and uncovering what happened with the mom. This way you wouldn’t have to rush the reveal and consequences.
Think of it as a detective chapter, maybe even with the chance to redeem or at least change her a bit.
Or you just go for the Amazonian Chosen Warrior Goddess Gina beating the shit out of now comparatively tiny executioner