NBA legend Kobe, 41, died along with 13-year-old Gianna – known as Gigi – and seven other people when the helicopter they were travelling in crashed in Calabasas, California last month.
And Vanessa, who was married to La Lakers icon Kobe for 19 years, says she is determined to stay strong for the couple’s other three daughters Natalia, Bianka and Capri.
Alongside a video of Kobe coaching Gigi and her basketball teammates, Vanessa wrote: “I’ve been reluctant to put my feelings into words.
“My brain refuses to accept that both Kobe and Gigi are gone. I can’t process both at the same time.
“It’s like I’m trying to process Kobe being gone but my body refuses to accept my Gigi will never come back to me.
“It feels wrong. Why should I be able to wake up another day when my baby girl isn’t being able to have that opportunity?!
“I’m so mad. She had so much life to live. Then I realize I need to be strong and be here for my 3 daughters.
“Mad I’m not with Kobe and Gigi but thankful I’m here with Natalia, Bianka and Capri.”
Kobe and Gigi were travelling to a basketball tournament on January 26 when the helicopter they were in crashed in foggy conditions.
All nine people on board the aircraft died, including Orange Coast College baseball coach John Altobelli, 56, his wife Keri, their daughter Alyssa and Harbor Day School assistant coach Christina Mauser.
Another young player, Payton Chester, was also killed along with her mother Sarah Chester, and pilot Ara Zobayan.
Vanessa, 37, added she was praying for all the victims of the devastating tragedy.
She said: “I know what I’m feeling is normal. It’s part of the grieving process.
“I just wanted to share in case there’s anyone out there that’s experienced a loss like this.
“God I wish they were here and this nightmare would be over. Praying for all of the victims of this horrible tragedy. Please continue to pray for all.”