Complex sentence: He had a fractured relationship with his mother due to her suffering from bi-polar disorder and became rebellious, he constantly went out of his way to scare his mother and in December 1999, he had an argument with his father, punching him.
Split into simpler sentences: He had a fractured relationship with his mother due to her suffering from bi-polar disorder, he would constantly went out of his way to scare her. In December 1999, he had an argument with his father, punching him.