Of course it's someone else's fault. It always is. I am still unpaid from several years back, for printing services and data base cleanup for the amount of $5,000.00. You really had a good thing going.
The thing is, I got paid thousands of dollars for numerous other jobs, until one day you say we did "shotty" work; I did copy editing also for her.
She used the legalese on me too and the threats. She wrote the check to pay me, then closed the checking account that afternoon.
She seems kind of unbalanced in the head the last few years, so be very wary in dealing with her.