Small World by Laura Zigman

From bestselling author Laura Zigman comes a heartfelt novel about two offbeat and newly divorced sisters who move in together as adults—and finally reckon with their childhood
A year after her divorce, Joyce is settling into being single again. She likes her job archiving family photos and videos, and she's developed a secret comforting hobby: trolling the neighborhood social networking site, Small World, for posts that help solve life's easiest problems. When her older sister, Lydia, also divorced, calls to tell her she's moving back east from Los Angeles after almost thirty years away, Joyce invites Lydia to move into her Cambridge apartment. Temporarily. Just until she finds a place of her own.
But their unlikely cohabitation—not helped by annoying new neighbors upstairs—turns out to be the post-divorce rebound relationship Joyce hadn't planned on. Instead of forging the bond she always dreamed of having with Lydia, their...