Melissa Rivers found writing her new memoir "very cathartic."
The 47-year-old producer - who pays tribute to her late mother, Joan Rivers, who died following complications from an endoscopic procedure almost eight months ago, in 'The Book of Joan: Tales of Mirth, Mischief and Manipulation' - still misses the 81-year-old star "every day."
She said: "I never let myself imagine life without her. Why would I want to?"
Melissa struggles the most "when something really funny is happening" or when she gets off a flight.
She told PEOPLE magazine: "Who do you call and say you got there safely? Even if it's the middle of the night? That's when it really hits me. Getting in the car at the airport, and, you know, 'Who do I call?'
"Everybody asks me, 'Don't you feel her presence?' I do, but I don't. She'll leave me alone until I do something that really p***es her off, like cut bangs.
But Melissa claims sharing her memories of the comedienne in her new book was better than therapy.
She said: "It was very, very cathartic to write."
Her 14-year-old son Cooper is also trying to adjust to life without his grandmother, who was "his partner in crime."
She said: "He would get away with everything and she would indulge him. I would say to her, 'Are you really trying to undermine all my authority?' And she'd say, 'Yeah, pretty much. Being a grandparent is the best because it's all of the fun and none of the c**p.' "