Cristina was eleven months younger than her sister Frida, and the pair were very close, and Frida used Cristina as an indirect and direct subject for some of her paintings.
Cristina later married and had two children, Isolda and Antonio. Cristina's husband left her after the birth of Antonio. When Frida and her husband Diego Rivera returned to Mexico as successful painters, Cristina acted as subject for both artists. She was one of Diego's favorite subjects, and he often painted her in the nude. Soon after her husband left, Cristina and Diego began an affair.
Rivera portrays Cristina in his art work, and she was one of his favorite models. Cristina was depicted on the South Wall of Rivera's mural The History of Mexico: The World of Today and Tomorrow. She lies at the bottom of the mural alongside her children and Frida. This could be an indication of her importance to Diego. Pairing Frida and Cristina and her children showed the contradictions between the two. Frida appears statuesque while Cristina appears "lively." Another contradiction was the aspect of Cristina being his lover and Frida his wife; and in addition Cristina had children and Frida did not.
Cristina is also an indirect subject of Frida's 1937 painting Memory, the Heart, a self-portrait displaying Frida with a metal rod going through an empty space in her chest. Art historians have suggested that this symbolizes "displacement of penetration." In other words symbolizing Cristina's affair with Diego. The pole replacing her heart, which lies wounded and bleeding on the ground, also shows the immense pain which was the result of the affair.
Cristina also appears in Rivera's Figure of Knowledge, in the Ministry of Health. Depicted in the nude, she holds a yonic shaped flower as a symbol of her femininity. Diego depicted her in the nude in another mural in the same building, although neither of the nude depictions were meant to be erotic but represented a vision of health and purity.
Cristina and her children lived with Diego and Frida as a family. Towards the end of Frida's life, Cristina looked after her and made her as comfortable as possible. After Frida's death, Cristina lived her life separate from Diego. Diego turned Cristina and Frida's childhood house La Casa Azul in Coyoacán into a museum of Frida's work, though this didn't please Cristina.