Sounds like you handled it pretty well. Just remember(and it's hard to in the heat of the moment, I know) to not raise your voice; calm, cool and confident. It's business, not personal. Let her feel the financial hardships.
Keep it up! Don't roll over for her anymore. She will have to respect what you are doing. I'm sure she won't like it but who cares? She will respect it and that's a good thing.
