"She was charming and sweet and beautiful and lovely," Reis Brooks tells PEOPLE.
The pair met one day when Brown was getting pizza delivered to her Atlanta-area townhouse. "I remember her opening the door with [her boyfriend] Nick [Gordon] and I waved and said, 'I am your new neighbor.' And being the sweetheart that she is, she ran out and gave me a hug," says Reis Brooks. "From that day forward we got to know each other very well."
Brown would often share stories of her mother, who died in 2012. "She adored her mom and missed her terribly," Reis Brooks says of Brown, who died on Sunday at the age of 22, almost six months after being found unconscious in the bathtub of her home.
"We would sit on my back deck and she would just sing me her mother's songs and show me picture after picture of her mom," she adds. "Krissy was very genuine and she really loved and missed her mama."
Reis Brown remembers her friend as affectionate and says she was full of "love and joy."
"She had a great spirit, a big heart and a killer smile," she says. "There was nothing like Krissy's smile. It's really hard to think I will never see her again."
Reporting by ELISSA ROSEN