Freeway II: Confessions of a Trickbaby

Crystal "White Girl" Van Meter is a 15-year-old prostitute who is sentenced to 25 years for a long list of crimes which include beating up and robbing johns. Transferred to a minimum security hospital to seek treatment for bulimia, White Girl teams up with Angela "Cyclona" Garcia, a lesbian teenage serial killer. Together, they escape from the hospital, despite White Girl injuring herself on a barbed-wire fence. Cyclona is convinced her beloved Sister Gomez can help "White Girl" with her eating disorder and they head to Tijuana. On the way, Cyclona murders a family and has sex with the dead bodies. "White Girl" is not happy that Cyclona has stopped taking her meds and insists she continue to take occasional doses should they continue together. They steal the family's car and make their way south. On the way, Cyclona reveals how Sister Gomez saved her from being molested by her father and possibly aliens. After drinking one too many beers and huffing some paint, they crash and fall down a hill laughing.
Undaunted, the two fugitives catch a ride on a freight train only to be assaulted by a transient crack addict. Cyclona kills him to protect White Girl, and the two make off with his bag of crack and guns. Venturing into the woods, they leave a trail of crack which is picked away by shady men with crow feathers on their hats. Lost and confused, they make it to the border only to have a stand-off with two customs officials, both of whom Cyclona kills. "White Girl" violently pistol-whips Cyclona and after making her point, the two race to the suburbs of Tijuana.
In Tijuana, Crystal/White Girl makes money by luring men to dark alleys on the promise of a good time, and mugging them. Cyclona and White Girl check into a run-down motel where they have a moment with beer, a shower and a vibrating bed. White Girl finally gives into Cyclona's sexual advances toward her and the two of them engage in some rampant lesbian sex.
After a few days, the two lovers find a poster that shows Sister Gomez is in town. Sister Gomez appears to be a Catholic/spiritualist healer; Cyclona is very keen that they visit her, for Sister Gomez has protected her from abuse in the past, and might be able to help them. They visit Sister Gomez at her gaudy mission house. Sister makes an enormous roast feast for her "little movie star" (Cyclona) and the friend "with the hungry demon" (Crystal), referring to her bulimia. Cyclona then disappears as White Girl is forced to work for Sister Gomez in the same way as she has been doing, in exchange for food. Finally, Crystal grows weary and makes her way to the basement, where she finds small children in a bondage room with a U.F.O shaped lantern. There is blood everywhere. Cyclona is hanging half-nude in a bondage style contraption. She tells Crystal that Sister Gomez made her watch while she chopped up children and made food out of them. She reveals that her ultimate plan for Crystal was to fatten her up with the meat of the children, and then, serve Crystal up for dinner as well. Crystal concludes that Sister Gomez is the witch-leader of a bizarre cult that rapes and eats children and then sells the child porn videos, protected by the front of a Catholic mission. Ready to deliver justice, White Girl/Crystal frees Cyclona and kills all the cult members; she also reveals Sister Gomez to be a rather well-endowed man. Not succumbing to bullets, Gomez is thrown in the oven. Burning, Gomez screams of his 100,000 years of terror and the revenge from his father Jupiter that will ensue. Crystal, keeping a promise made earlier, is forced to kill Cyclona in a tearful scene rather than allow her to be captured. Cyclona, wishing to leave behind a life of abuse and violence, hopes to be reincarnated as an eagle (we discover that Sister Gomez was her earliest abuser). White Girl makes a deal with the federales and leaves with her lawyer/pimp, stating "I'm not hungry anymore."

Question: Why does Crystal kill Cyclona?