Jack Schlossberg has spoken out about the impact of his older sister and “best friend” Tatiana’s death. The 35-year-old granddaughter of the late President John F. Kennedy and Jacqueline Kennedy Onassis died in December 2025, after being diagnosed withacute myeloid leukemia, an aggressive form of blood cancer, with a mutation called Inversion 3. During a new interview with Vanity Fair , Jack opened up about managing his grief over the past few months, confessing that he doesn’t think he’ll ever “process” it. “The world will never be the same for me, not only since she passed away, but since she was diagnosed with cancer about two years ago,” the 33-year-old , who’s running for Congress in New York’s 12th District, said. “She was my best friend. We could finish each other’s sentences. And no one loved me or was a bigger fan of me of anyone else than my sister. “So I miss her all the time. Every day I think about her.…