Complex sentence: Upon reaching 18 years, April left her adoptive family for good, after having one last row with her father (and severely injuring him in process) and without a word of goodbye to her mother, and left for Newport, a big industrial megapolis.
Split into simpler sentences: Upon reaching 18 years, April left her adoptive family forever, after having one last row with her father, wherein he was injured. Without a word of goodbye to her mother, April left for Newport, a big industrial megapolis.