While it's unclear in the finale who exactly let Georgia's latest murder leak to the cops, it's made pretty clear that it was likely Nick and his ex-boyfriend/undercover private investigator Gabriel Cordova. As Nick is on his way to Georgia's wedding, Gabriel stops him and tells him the entire truth about who he really is and who Georgia really is.
Gabriel even warns Nick that Georgia is "dangerous."
In an earlier episode, when Nick goes to Tom's funeral, he casually says to Gabriel that Georgia was present for Tom's death.
Knowing plenty about Georgia and Cynthia's rivalry and little about their newfound alliance, Gabriel surmises that Georgia was responsible for Tom's death based on her past. So, will Georgia have a good alibi in Season 3?