Is it normal to leave a friend after this incident...

Last year, my friend had this idea to publish and sell a book that he wrote when he was younger. Since I like to draw, he asked me if I can help draw some of the characters and images for his book. Of course, I agreed and asked to read his book so I can get a better understanding of the characters and the story. However, later that day, he calls me up and asks me to read his book and rewrite the whole story. So in short, he wanted me to do all the work for his book while he does absolutely nothing. I asked him why can't he rewrite the story and he just tells me that he's too busy with school. Are you serious?! When I was in high school, I made a comic book of my own without anyone's help while taking 6 classes. Yet this guy was only taking one class in college and could not pull his weight to help out? Plus, this was his book so he should have been the one to rewrite the story or whatever, not me. Not only that, but during that time, I was working on another comic book of my own, and he told me to put that off for a while to help him sell his book. Because of that, I stopped talking to him, and cut him out of my life. I feel bad for doing it, but he was just out of control. He wanted me to stop my own project just so I can focus more on his while he does nothing to help out. This guy did have a tendency to always ask me for favors, but this was the last straw, and I just could not take it anymore.