Maybe not discredit Susan as much as give her a slice of humble pie. I think a nice ending would be [player] and Susan getting along after the incident is resolved. At that point Susan would have to respect her as an adventurer for doing what she could not and fixing the problem she created. If [player] shows the grace to save Susan from destruction, I'm sure Susan wouldn't be so bent out of shape around [player] anymore.
And *New Game+* would have a special trinket or something from Susan as a token of gratitude in the next file

Such a happy ending!