Just as a point of advice, sometimes these things are necessary in order to help us learn. Its hard when you are in the thick of a relationship-gone-sour to step back (I know this, believe me!), but it can actually be a good thing in the long run.
I have had a fair few projects that have taught me valuable lessons about how to do things better, or how to be clearer, and even how to draw a line in the sand and say "no, I am not accepting this". I have had clients take advantage of my "soft" approach in the past and it has forced me to step back and learn from it as best I can.
My quote/brief/plan/contract document has progressed SO much over the years - and with every single project I look over it and evaluate it to see if I can improve... and I always do.
I have also learned that what is written down in a contract/spec and how you choose to enforce it are very different things. There is no point having a contract unless you are prepared to enforce the terms, and behave in a way that is consistent with it. I now no longer do ANY work in good faith. To me, the only good faith is payment
Anyway, best of luck, client relationships can be difficult... but it really is a matter of learning from our mistakes, or tweaking our processes to try and prevent it happening again.