Lets pretend she REALLY wants to understand rather than argue. Tell her you dont want to argue but you understand she needs clarification. Tell her you do not need justification but since she says she doesnt know what she did you'd be happy to type up an email or letter to her. She will protest and insist that isnt the right way or what she wants. SO repeat yourself- you do not want a discussion because it will lead to a fight so this is the best way you can honor her wishes in wanting to understand while protecting yourself and honoring you own wishes. Then write the email and be as non-confrontational and explicitly explain everything down to the last detail. Then give it to her or click send. Everything else that follows will be on her.