Kristen’s plan was for Eric to zero memory of the event. Nicole wasn’t supposed to show up and find him and get him to medical attention, which is probably why he started having the memories. So then in that respect, Nicole showing up is yet another pain in Kristen’s neck. Kristen’s perfect plan was probably counting on Nicole to be alone in her room at the convent, dreaming of Eric, not having an alibi for when Kristen dropped the video bomb.