Ok there are so many stories with caught in the title but here are some more details:
Girl is a house sitter / maid (not 100% sure)
She thinks she is going to alone all day has BF come over, the mom comes home so the BF hides in the closet, the mom & girl go at it, the son comes home, the mom hides in the closet with the BF. it was posted on here but the site doesn’t load anymore.
Source: reddit.com/r/eroticliterature/comments/8jwbln/request_looking_for_a_story_with_caught_in_the