OMG>>>>NEVER SAW ALL THIS COMING maybe another lessoned learned

[Fun&care]

The only thing you can do, is go over every one of her complaints with her and explain to her why you do things the way you do. Which you said you did. That's it. That's all you can do. If she wants to leave, she is free to do so. I know it's hard, but you have to toughen up. There are going to be clients like this. Try to think of it as business as much as possible, and not take it to a personal level. She is not necessarily criticizing YOU she is criticizing your BUSINESS. I find this helps me when I have a difficult client.