She Started It by Sian Gilbert

Annabel, Esther, Tanya, and Chloe are best friends - or were, as children. They drifted apart in adulthood, but shared secrets have kept them bonded for better or worse, even as their childhood dreams haven’t quite turned out as they’d hoped. Then one day they receive a wholly unexpected invitation from another old friend. Poppy Greer has invited them all to her extravagant bachelorette party: three days of white sand, cocktails, and relaxation on a luxe private island in the Bahamas.