After finding Vivian's body and realizing she is now free to speak, Nerissa shows up at the Crooked Man's trial and claims to have witnessed him ordering Georgie to murder Faith and Lily. Alternatively, if Bigby killed him at the foundry, then she will show up and reveal what really happened with him.
Later, the next morning, she then admits to Bigby at the end of this episode that she lied to seal the trial, and that she is the one who placed Faith's head at the Woodlands for Bigby to find. As she walks away, Bigby notices similarities between things she, and Faith, have both said to him that make him question who she really is and what's going on.