Let her vent

1) Do not interrupt her, even if she disrespect you.
2) Listen to her every single word.
3) Do not fear or panic to what she says.
4) Repeat back to her a summary of what you heard her say.
5) Let her calm down.
6) Tell her thank you for expressing her feelings.

Why?
Give her this freedom or she will privately tell someone else.
Wouldn't you rether hear it from her. And have her to you then
someone else.