You had the diplomatic quest, right? I think you need that.
Otherwise I would suggest trying again. You have to beat a good deal in any case.
I assume you have that quest, so next time just beat her, if she just dies then it's probably a bug of sorts. But I would assume she backs down. Some time since that quest so I can't remember how much beating it requires.
And I killed the wrestling partner too, a smart thing to do as giants hit really hard. And she didn't seem to mind.