That might have been part of it (although I would think that scene would've been days or even weeks later so, if they were going to kill him, I would expect them to have done it already).
I think, in the end, she did it to protect them. I guess despite everything she still wanted to protect them, or maybe she was thinking of the boy who saved her (although they probably killed him first change they got for letting her go).
I don't know if I would be as forgiving as she was after everything she went through. All I could think about was Jennifer Aniston's character on "South Park".