It sounds like O.J. Berman has everything under control, but Holly doesn't actually get out of jail that first night. The narrator wants to feed her cat, but he has no key so he has to get into her apartment through the window.
He finds the cat in Holly's bedroom, but he also finds a man in there who looks like José and who's packing up all of José's stuff. The narrator asks about José's whereabouts, but his cousin either isn't sure about this or just isn't willing to tell the narrator. He hands a letter to the narrator and asks that he give it to Holly on behalf of José. It's addressed very formally to "Miss H. Golightly – Courtesy Bearer (doesn't exactly sound like a passionate love letter, does it?).
The narrator is so sad for Holly and he hugs the cat as he thinks about how crushed Holly will be when she realizes that José has left her.