You're doing better than I would in the same situation. My training comes straight from the queen of righteous indignation. I've seen, and cowered, as my mother held her ground and demanded, and demanded, and demanded, AND DEMANDED,
AND DEMAAAANNNNDED what she thought was right. It's terrifying, really, and has taken me years to learn that that's not the best way to deal with people.
Every so often, though, the skill comes in handy.
She looks kinda pissed, wouldn't you say?