Massacre is noted on page 38 of Wide Sargasso Sea and is significant to the novel, as it is the village where the unnamed narrator and Antoinette have their honeymoon. The footnote listed at the bottom of the page further explains that the village is near Rhys's birthplace, Roseau.
This location illustrates the importance of recognizing the history of slavery in the region and the alienation enslaved individuals felt. Though this isn't elaborated on in the text, it is tied to the island's colonial past. What is really interesting about this is that Antoinette tells her husband that no one from the village actually recalls what slavery was like on the island. This idea of suppressed memory reminds me of how Antoinette ignores warning signals, like seeing dead animals. It also foreshadows her future and the destruction of her life and identity.
Mapping this location on COVE reveals how the history behind Massacre deepens the novel's plot and adds more complexity to Antoinette's character. By linking the history of the village to Antoinette's past, Rhys highlights cultural destruction and the influence that patriarchal figures (like colonizers or Antoinette's unnamed husband) have over the region. 
Source: Wide Sargasso Sea by Jean Rhys