These verses show Judah's mighty change of character...
Remember back in Genesis 38:26 Judah see's how badly he's been treating his family an has that might change of heart and a realisation of how much better he can do. This reaction here shows Joseph that Judah has indeed changed and made great efforts to be the man and brother God wants him to be. It's so much easier to forgive when you see real change in the offending parties!