Lively also wrote about the "painful" film industry in her heartfelt tribute to her former costarBlake Lively is encouraging others to "hold those you love" close in the wake of her Gossip Girl costar Michelle Trachtenberg's sudden death at age 39 on Feb.

Blake Lively paid tribute to her Gossip Girl costar Michelle Trachtenberg. Yesterday, news emerged that the actor had died at age 39. Though her cause of death is still unknown, police sources noted that she recently underwent a liver transplant.

Trachtenberg starred in 28 episodes of “Gossip Girl” as Georgina Sparks, a recurring character and frenemy of Lively’s Serena van der Woodsen. Georgina, also a member of the Upper East Side’s high society, was notoriously rebellious and known for getting herself and those around her into trouble.