Complex sentence: After trying to hire a nanny to watch his son, he began sleeping with her, and while having sex with her one night, he found out that she had been giving Wilber cough medicine to keep the baby quiet.
Split into simpler sentences: After trying to hire a nanny to watch his son, he begins sleeping with her. While having sex with her one night, he finds out that she had been giving Wilber cough medicine to keep the baby quiet.