Few TV shows mastered the art of whiplash like The Big C. One minute, Cathy Jamison is burning a couch or skinny-dipping and then in the next, she’s hiding Stage IV melanoma from her husband. Laura Linney is doing Olympic-level nuance. But fans still ask: When does Cathy finally tell Paul the truth?The answer lands in Season 1 Episode 9 (titled The Ecstasy and the Agony), a half hour that starts with a driving lesson and ends with one of the series’ most gut-punching reveals. And because this is The Big C, the confession arrives next to ecstasy pills and a car crash. Yes, the show lives up to its name.Let’s break down the moment when Cathy stops running, and Paul starts!When does Cathy tell Paul about her cancer on The Big C?By the time Episode 9 begins, Cathy is deep into her secrecy era. She’s juggling her diagnosis with a desire to feel alive again, and that sometimes happens in ways that are questionable and illegal. Case in point: she takes ecstasy with Lenny on her back porch because she "needs an escape."Meanwhile, Paul gets promoted at work and spirals into a celebratory dinner meltdown because he is clueless and frustrated. He drinks too much, gives an inappropriate speech, and tells his coworkers he walked in on Cathy "with a black guy," which...is actually what happened.While Cathy and Lenny embark on a chemical existential trip in their backyard "pool hole," their teenage son, Adam, is having his own misadventures. Paul walks out of the dinner to go pick Adam up from a house party. But since Adam is too drunk to drive, he lets his son do so. Then they hit a tree.Both parents meet at the ER. Adam was hurt, Paul was shaken, and Cathy had to deal with the fallout from her choices. Following them is Dr. Mauer, who rashly accuses Paul of "moving out on Cathy after she got sick." Paul stops moving. The last person to hear Cathy's secret was the one who should have been aware of it from the very start.Why does Paul want to divorce Cathy on The Big C? After Dr. Mauer confronts her, Cathy has no way to run from reality any longer. She walks up to Paul in the waiting room, prepared to tell him what she has been hiding since the premiere. We have been looking forward to her taking that breath for the last nine episodes of The Big C. View this post on Instagram Instagram PostAnd then Paul beats her to it as he says:"I want a divorce."Hold on, what? Cathy comes to for honesty just as Paul gives up. The irony is awful, and the reveal is messier than even Cathy's backyard. So it is by episode 9 of The Big C that the doctor ends up blowing Cathy's carefully maintained and well-thought-out cover, which only leaves her to confess something she was trying to avoid for the entire duration of the show till now. Thankfully, Paul realizes what happened and gets intricately bound with Cathy's cancer journey, for better or for worse, from this point on.All four seasons of The Big C are now on Netflix.