Supergirl, who's got info on Cat's attack/rape, gets the other Lena & arrests her with the help of the DEO. Meanwhile, Lillian goes to see Carter, who really isn't dead, who got turned into a new & improved Worldkiller that's retrofitted with Red K; which turns a Kryptonian evil. The new Worldkiller decides to strike on a nice day & he's able to get a shot of it off, in a few hours the effects'll take place & these'll cause her to attack/rape Cat. This happens at the end of a workday when she's about to put on her coat. She gets a hand put over her mouth, her clothes ripped off & she tries to fight off her attacker to no avail. She yells at Supergirl to stop but the other isn't having any of it. Supergirl turns her over, ties her up & rapes her from behind. Once it ends Supergirl leaves the other, a few hours later she decides to leave National City & joins the Legion of Doom in Starling City.
It takes Teams Arrow, Flash & Legends months to get rid of them but when they do they end up celebrating in Gotham & during that time the DEO realize what happened to Kara so they mount a rescue mission but 1st they get Lillian & in extension they find CADMUS as well as Carter being alive. A few months later, when the Red K wears off, Kara returns to face her actions. It takes a while but eventually Cat forgives her & they start their relationship anew. They also become fast friends with the real Lena Luthor; this relationship enables them to've Lena use LCORP technology to reverse the Worldkiller syndrome in Carter, a few years later he goes to college, when he graduates he becomes an astrophysics' assistant & later gets married. Also, everyone else lives happily ever after & all's well.