The monsters scare the child as it symbolise the mother being angry and shouting at the kid.
When the mother is drunk, she gets angry, creating monsters. She decided to keep the child as Justin was abusive that could have a bad influence on David.
This turned the mother to depression thus her drinking more. After David ( the toddler you play as) was born and turned 1, the 2 parents decided to break up and divorce. However, Zoey turned alcoholic and Justin was abusive. In the beginning, Zoey and Justin married.
