Joan's daughter opens up about the loss of her mom and how she's moving on
Credit: Justin Coit

Melissa Rivers shares her personal memories of her mother, Joan, and the lessons she taught her about laughter and love. Subscribe now for instant access to this exclusive interview, only in PEOPLE.

It’s been almost eight months since Joan Rivers passed away at age 81 following complications from an endoscopic procedure, but her daughter Melissa says she’s finally not counting the hours or days since.

“I never let myself imagine life without her,” Melissa exclusively tells PEOPLE in this week’s issue. “Why would I want to?”

In a new memoir, The Book of Joan: Tales of Mirth, Mischief and Manipulation, Melissa pays tribute to her mom, recalling an upbringing that was filled with love and laughter. From Joan’s obsessions with true crime, which Melissa shared, to their tales of working hundreds of red carpets together, the book could have been called “Cheaper than Therapy!” says Melissa, laughing. “It was very, very cathartic to write.”

While the world mourned her celebrity, Joan’s absence was an extremely hard adjustment for Melissa, 47, and her 14-year-old son, Cooper, at home.

“Who do you call and say you got there safely? Even if it’s the middle of the night?” she says. “That’s when it really hits me. Getting in the car at the airport, and, you know, ‘Who do I call?’ ”

Cooper “has lost his partner in crime,” Melissa adds. “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 crap.’ ”

Going through Joan’s belongings has been a process, says Melissa, who put her mom’s New York apartment up for sale and plans to auction off most of its contents. Knowing that her mom liked to stash away fun money around her house, mostly in ones and fives, Melissa has even had to shake out books and magazines.

“Then I was told she used Milk Duds boxes as her travel wallets,” she says. “And we’ve been throwing things out!”

Rivers also recently spoke at the signature charity event for Our House Grief Support Center for which she has been an ambassador this past year. The center has honored her previously for her philanthropic work as well as her openness in discussing grief with honesty and dignity.

The times she misses her mom the most “are when something really funny is happening,” Melissa adds. “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 pisses her off, like cut bangs.”

For more of Melissa Rivers’s exclusive photo shoot and at-home interview – in which she opens up about Joan’s final days and her new relationship – pick up the latest issue of PEOPLE, on newsstands Friday

Melissa Rivers Reveals When She Misses Joan Most