Complex sentence: When Michael visits Tommy's father in prison he finds out that Tommy's mother misused him as a lover and slept with him regularly, the reason why the father, who came home early one day, bludgeoned the mother to death.
Split into simpler sentences: When Michael visits Tommy's father in prison he finds out that Tommy's mother misused the boy as a lover and slept with him regularly. This is the reason why the father, who came home early one day, bludgeoned the mother to death.