What is your worst most difficult client story ever?

I am dealing with my worst client ever. I have a startup video production company specializing in video production, video editing and 2d animation services. One of my current clients is a singer whom wants a 2d animated music video. Working with her the past few days, I have noticed she gets hung up on the smallest things, and thinks she knows better than me. Last night I was on a call with her for nearly an hour long, arguing back and forth on something so miniscule. She called me because I had emailed her that the pictures she sent me won't be good to use for the animation style I am going for. I asked her for a clear profile headshot. She eventually sent the right images.When I received the images, I replied back that the new images are perfect, I can use these pictures as your other image had your shoulders cut off. This is when she called me.She started going off on me how that the first images she sent me were fine. She said technology is so advanced these days, so why don't I scale the images down to see her shoulders. Keep in mind that the image she sent me had her shoulder cut off, so what would scaling do? This statement makes no sense at all as the animation design has nothing to do with scaling, but I need to sketch over the head and shoulders. Her hair was also cut off in the first images which is why I told her to send new ones. She goes on to say that she has done some video editing and knows what she is talking about( keep in mind I am animating for this project not video editing, but I guess she knows best). This client will ask questions that are of now importance at all and will even try question how I do things when she has zero professional knowledge of this line of work. I feel like giving this client a tombstone piledriver the way she is getting on my nervous and try to act like she knows my line of work. She even said that what I charged her is a bit overpriced for what I am doing. I explained to her the process of animation and that it is very time consuming. I gave her a huge discount and she still thought I am overpriced. I pray to God I can keep my temper under control during the course of the project.You ever dealt with a difficult client like this? see hubwealthy.com/wealthy