Katherine Schwarzenegger is bonding with fellow new mom, Nikki Bella, and her twin sister, Brie Bella!The 30-year-old author (who welcomed her first child, baby girl Lyla, with Chris Pratt in August) went live on Instagram with the Bella twins, 36, on Thursday to have a candid discussion about all things motherhood.During the chat, Nikki got real about postpartum depression, admitting that she first started feeling lonely throughout her pregnancy, mostly due to the coronavirus pandemic.