"Coop and I took our annual family vacation to Wyoming," the new "Fashion Police" co-host told "Entertainment Tonight". "[The] first without my mom and scattered some of her ashes there so we can still be together every August as a family."
Asked how she and Cooper, who starts ninth grade this year, have been coping since Joan's death, Rivers said, "Cooper and I talk about what would be the best way to honor her legacy, and the best way to honor her legacy is to be OK."
Joan died unexpectedly last Sept. 4 at the age of 81.
Rivers shared how she and her son will mark the one-year anniversary on Friday.
"Everyone expects me to have this big grand plan for the 4th and I am just going to be spending it with my son," she told "ET." He is going to go to school, I am going to go to work and come home and light a candle, and have a glass of wine."
"I'm kind of a disaster this week," she confessed, adding, "the greatest way to honor my mother's legacy is to keep going because she was not a quitter."