I have it right in my contracts that if we end up in court over money all court fees are the responsibility of the client (meaning they have to pay all court fees). I've only ever had to threaten it once...got my money within a couple days. For $500 I would for sure take it to small claims, plus the way she treated you and spoke to you...I would do it just on principle alone! Sorry your going through this and hopefully you get what is rightfully owed to you!