The morning after his night gambling, Jos dolls himself up as best as he can and goes to visit Becky.
She lives on the upper floor (i.e., the cheapest room) of a quasi-Bohemian kind of hotel where all sorts of people from students to traveling merchants are staying. It's not a nice place, but Becky kind of loves it there. She has reverted almost entirely to the kind of life she led as a little girl with her artist father. She's full of life and happy to be in the thick of relative seediness.
When Jos knocks she quickly hides her liquor, lets him in the room, and immediately begins to tell him her story.
Her version is that she is blameless and a victim of the Crawley family's evil scheming. Also running through her story is the implication that she is still deeply in love with Jos.
After a while, Jos "went away, convinced that she was the most virtuous, as she was one of the most fascinating of women, and revolving in his mind all sorts of benevolent schemes for her welfare" (65.18). So yeah, Becky can still bring it.
Jos tells Amelia and Dobbin about how sad and miserable Becky is. Dobbin is all, yeah right. But as soon as she hears that Becky was "forced" to give up little Rawdon Jr., Amelia decides to go visit her and try to make her feel better.
The three of them get ready and make their way to Becky's hotel.
When they get there, Amelia runs and hugs and kisses Becky.