Mental illness

Today I just watched a short film. A lady who just gave birth to a baby boy. Her husband always play game or chatting on phone. He even neglect his wife when his wife just asking for help doing house chores. He told his wife not wife should doing all house chores. Lucky her oldest daughter always help her to look after newborn baby. One day the lady can't stand with her husband always playing game on phone and they argue. At the end the lady killed her oldest daughter. What moral that we can learn in this story?