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Sylvester Stallone is mourning the death of his half sister just six weeks after losing his son.

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The "Rocky" star's 36-year-old son, Sage, was found dead in Los Angeles last month, and the family was struck by tragedy again on Sunday when the actor's half sister, Toni Ann Filiti, lost her battle with lung cancer.

The 48-year-old passed away at the home of her mother, Jackie, in Santa Monica, Calif., on Sunday morning.

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Jackie tells the New York Daily News, "I was holding her in my arms. I had just washed [her] face and told her how pretty she looked, and she just fell asleep ... She's too young to go, but she wasn't feeling any pain. What a terrible month. First Sage and now Toni. It's hard. At least they're together now in heaven."

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The 90-year-old reveals her superstar son was devastated by the news of Toni's death, but has vowed to remain close to her son. She adds, "He said he can't take any more pain. He said he'll always be there for her son."