In the opening scene of this episode, Marlene snaps some sense into Cathy... literally! She says that having cancer doesn't give her an excuse to act like a destructive bitch. Cathy takes that cue and sets about making her life right.
She visits Andrea at home and discovers life is actually pretty great for this student. She has a loving family and sings in the church choir. Cathy then stands up in that church, asks the congregation to pray for her and and begs Andrea to return to school, as she had earlier threatened to drop out. It works, and Andrea tells Cathy she'll see her in class.
Cathy also tells Adam that life is short and he should apologize to Andrea for their fight. He actually listens and, after Andrea make him lick her locker, these two are pals again.
Elsewhere, Cathy makes up with Rebecca, who was withholding sex from Sean because she felt bad about how awful a friend she has been to Cathy. These former college roommates bond on Cathy's porch.
Finally, the big moment: Cathy knocks on Paul's door. She isn't even bothered by seeing Tina, the rugby slut, there and doesn't yell at Paul when he says they had sex. Instead, the episode concludes with her finally admitting: I have cancer.