Secretly Pregnant with the Billionaire's Daughter

Rachel is an heiress, and she goes after the new personal assistant at Ethan's company with bullying that does not let up and, later, with schemes against the life of the assistant's child. The assistant is a woman named Isabel. Six years ago Isabel was a college student who was set up by someone, and the setup put her in bed with Ethan, who is the heir to a billionaire fortune. She got pregnant, dropped out of school, and has been raising the child alone since then. The child has severe allergies, and Isabel works without rest to raise them. Getting hired at Ethan's company happened by chance. Isabel fights back each time Rachel comes at her. Ethan steps in to protect her more than once, and the days and nights they spend working together end with him in love with her. Around the same time, Ethan's great-grandmother Olivia finds out whose child Isabel has been raising.