It depends on your mental state. If you're easily affected by disturbing content, it might not be advisable. But if you can handle it, it can be a learning experience about the dark side of humanity.
The story shows Dahmer as a person who was able to hide his true self for a long time. He seemed like an ordinary guy to his neighbors, but in reality, he was leading a double life filled with horror. It also delves into his possible motives, like his fascination with death and his need for control, which made him into the serial killer he became.
Definitely real. Jeffrey Dahmer committed heinous crimes that were well documented and reported. His actions and the events surrounding them are based on actual occurrences.