"Our hearts are shattered. We will love you forever. She was a once-in-a-lifetime gal. A mother, daughter, sister and a truly exceptional wife. She was an artist, a musician, an entrepreneur and a true renaissance woman. She was the love of my life and I will miss her always," Brown wrote on the Facebook page of Red Arrow Workshop, the Lafayette, Louisiana, gift shop the couple ran.
Johnson, 33, of Lafayette, was one of two moviegoers killed Thursday when a gunman opened fire during a screening of Trainwreck. The gunman, John Russell Houser, 59, killed himself after the shootings, according to police.
Brown, who said the family also mourned for victim Mayci Breaux, said Johnson's best friend was also with her in the theater.
"This was a senseless act and, as is the case with all such acts, there is no playbook, no rules on how to cope," Brown wrote. "We're trying our best to pull ourselves together. We're putting one foot in front of the other."
Numerous other people posted Facebook messages of love and support for Johnson, who was in an all-female band called The Figs.
"She was an amazing artist, creative beyond belief, she brightened the world everywhere she went, she inspired and believed in people and was a great friend and confidant," wrote friend Woody Pines.
Friends are also remembering the warmth and spirit of Breaux, 21, of Lafayette.
"You'd always see her with the biggest smile on her face," Victoria Stinson, 18, tells PEOPLE. "She always lit up the room."
Breaux was a first-year student at Louisiana State University in Eunice, in a two-year program studying radiologic technology to become an X-ray technician, said school spokesman Van Reed.
Stinson, who worked with Breaux at Coco Eros, a women's clothing boutique in Lafayette, said Breaux was passionate about working in medicine. Once, when Stinson mentioned that dissecting a cat in class was "gross," Breaux responded by saying: "I love that stuff."
Breaux was always a bright spot in the day. "She was so easy to get along with and talk to," Stinson says. "She was just like a ray of sunshine."
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