In Great Expectations, how did Joe prove to be Pip's savior in London? What regrets did Pip have after that? How did he make amends?

After Magwitch is captured, Pip is resolute in doing everything possible to help the injured man get out of prison. Pip finally realizes how much the convict did for him and sees his treatment of Joe in a negative light. Soon, however, Pip falls ill; back at the Temple, he floats in and out of consciousness. When he finally becomes fully conscious, he realizes that the dreams he was having of Joe were genuine perceptions: Joe has come up to London to stay with him. Joe tells Pip that he has been sick for a month. Pip finally feels real remorse for his previous behavior, calling on Joe to hit him and look angry. As Pip grows stronger, he struggles to communicate his true feelings to Joe, who pays off Pip’s debts and goes back to the marsh before Pip can figure out how to do so.
When Pip returns to the town, thinking he will propose to Biddy, he finds that Joe and Biddy have just gotten married. He tells them how much they mean to him, promises to repay Joe for the debts he paid off, and begs them both to say they forgive him. While he is away working in Cairo, they have a little boy and name him Pip.