Confronting the Blackmailer

Adam is a combat veteran with a demented sense of humor, which can be dry at times. He is on leave when he receives a call from his step sister for help. His step sister, Sarah, has just told him she is being blackmailed and threatened by his ex, the user. There's enough red flags in his sister's story, and his history with the user, that he had doubts on what's true and what's not before he even confronts his ex. his ex has an apartment right across the hall from his step sister. Who will he ultimately believe and what are the consequences of that choice ?