Art helped us process 9/11 in so many ways right after the attacks. But for me the breakthrough wouldn’t come for nearly five years, at a midtown Manhattan movie theater.The Tribeca Film Festival had decided in 2006 to open with a premiere of Paul Greengrass’ United 93, despite puzzling murmurs of “too soon.” (Is there a reverse statute of limitations for when artists can make sense of trauma?) Tribeca organizers — Robert De Niro, producing partner Jane Rosenthal and the rest of the staff of the healing-minded Manhattan film gathering — invited not only Greengrass and the many terrific workaday actors featured in the film but the family members of the victims and heroes of that titular flight’s hijacking.Covering the event for my employer at the time, I approached the old Ziegfeld Theater with a mix of curiosity and anxiety. I had lived through 9/11 — watched the towers burn from a downtown apartment window, stood in Union Square as people streamed in soot-filled and shell-shocked. Was a movie recalling, let alone reclaiming, that day what I needed?I couldn’t have been ready for what followed. The answer was a resounding yes, in ways impossible to anticipate. I felt it immediately, stepping on to the red carpet, as it were, with the family members clearly eager to share with me or anyone who would listen their memories of those who died. I wouldn’t call them happy or even content, but a certain relief seemed to light their eyes as they opened themselves up, for the first time or maybe the 500th time, to talk about the men, women and children who died on that plane as a sidewalk-full of reporters eagerly listened.The movie of course was dramatically effective, cinema at its urgent finest. Greengrass bringing us along, gently holding our hands from the early moments of Tuesday-morning banality, to the terror upon the realization of what was happening, to the activation that something had forever changed — a metaphor in celluloid for what we all went through in the lead-up to and aftermath of that incogitable day. Sitting through the film I couldn’t believe what the director and his cast had achieved — couldn’t believe that something that lived so abstractly in our minds could so viscerally be created in front of our eyes. And then, the film’s ending — the plane spins down, the screen goes dark, the sound stops. In any other theater the room would have fallen into a reverent silence. But the room wasn’t silent. It was filled with wailing. Waves and waves of wailing.I was sitting in the main section of that grand 20th-century palace, the loge right behind me. The family members were mainly sitting in that loge. When the movie ended they let out the most heartfelt, soulful, painful cries, each of them with their own rhythm and cadence, all combining into a tragic cacophony that, if I’m being honest, I still hear in my nightmares. Just the loudest crying and sobbing you’ve ever heard, coming from dozens and dozens of people, cascading like a surging river, unending, unavoidable.As the cries washed over me and everyone else who didn’t lose people on that day, they bridged a gap, between the victims and the onlookers, bringing all of us in the latter group into their grief in a way that I have never been brought into another’s grief before. It hit me then what Greengrass had done — he hadn’t just re-created a terrible event. He had given victims a chance to see their family members one last time. While we were watching a movie, they were watching their loved ones eat, talk, live, fight and, yes, die. (One compelling moment, in a darkly comic way, arrived in a crowded restroom after the screening when an actor who played a hijacker came face to face with a family member. You could feel the room bubble with tension — it was only a second of silence but it felt like an hour — until the family member put his hand gently on the actor’s shoulder and said “you were very brave.”)And then it hit me what Tribeca had done too: Invited all of these family members to experience that last-glimpse together. To turn private mourning into public bonding.