A Supporting Actress’s Guide to Saving Herself After Transmigrating into a Book

Reborn as a Villainess in a Historical Story, She Marries the Antagonist and Has His Child

I'm looking for a book where the female lead transmigrates into a supporting character and has a child with the male lead, who I think is five years old and very well-behaved. The original character abused the child, so the kid is very afraid of her. The original character schemed to sleep with the male lead and had his child. The male lead was a scholar.