Kim Kardashian Mourns Grandma Mary Jo's Death, Calls Her 'Forever Twin'

Kim Kardashian is gutted by the death of her grandmother, Mary Jo -- and she shared a heartbreaking tribute about how much the matriarch meant to her.

Shortly after Kris Jenner announced her mom's death, Kim shared her own lengthy message, along with a series of snaps with her late grandma MJ ... lamenting, "My sweet Grandma MJ, my best friend, my gossip buddy, my forever twin..."

Kim says ... "You taught all of us the importance of family, and those values are something we'll carry with us forever!!!!! You were the woman who showed me what it meant to be a hardworking businesswoman."

MJ became a fan favorite over the years through her appearances on the Kardashian family's various reality TV shows, where viewers got to know her quick wit, warm personality and close bond with her granddaughters -- Kim, Khloé, Kourtney, Kendall, Kylie and the rest of the family.

Kim's closing is a real tearjerker ... asking her Nana to give her late father, the famed Robert Kardashian, "a hug for me."

MJ was 91.