She may seem stand off-ish to you but you are breaking the contract and you seem rather bitter and rude about it.

Many people fall sick on black Friday and other 'special' days of the year. You are implying she lied and went shopping when you have no proof. I will hope you are not saying such things to people that know her as it would be considered slandering and puts her reputation on the line.

Pay her what you owe and move on, she deserves clients that trust and respect her.