Literary devices are things such as

Literary devices are things such as Irony, Metaphors, Similes, Foreshadowing, Epiphany, etc...
I'm doing the same project and here is some that I found

Irony

‘‘The most prudent girls aren’t always prudent.’’ – Ansley
This statement is ironic because prudent means moral, cautious, but Mrs. Ansley went to the Colosseum and slept with Delphin and had his baby.

‘‘You had been out late sightseeing, hadn’t you, that night.’’ – Slade
Ansley is not sightseeing but sleeping with Mrs. Slade’s fiancé.

‘‘I’m sorry for you.’’ – Ansley
This statement is ironic because Mrs. Ansley is not only sorry for her not waiting for Delphin, but also for Mrs. Slade’s life. She is sorry that even Mrs. Slade marries to Delphin, Ansley herself has Delphin’s brilliant daughter.

‘‘After all, I had everything; I had him for twenty-five years. And you had nothing but that one letter that he didn’t write.’’ – Slade
This is an ironic statement because the audience and Slade are soon going to know that Mrs. Ansley does have everything because she has Barbara, the more brilliant daughter of Delphin.

The letter is also an ironic because the original purpose of it to make Ansley sick so that Mrs. Slade can get the man she wants. But instead of doing that, it helps Mrs. Ansley to have the affair with Delphin and even had his baby afterward.
The Roman Fever or the pneumonia is ironic because Mrs. Ansley was really sick because she was pregnant.
Foreshadowing

‘‘A full moon night, they would remember…’’
It foreshadows that something huge is going to be exposed this night.

‘‘Mrs. Ansley had always been rather sorry for her’’
This statement reveals that the reason of her feeling sorry for Slade is going to be known soon.

‘‘But she really sent her because they were in love with the same man –’’
The story of Great-aunt Harriet foreshadows that has happened to Slade and Ansley. Mrs. Slade and Ansley were in love with the same man, thus Mrs. Slade sent Ansley so that she would be ill.

‘‘They said Aunt Harriet confessed it years afterward.’’
It foreshadows that Mrs. Slade is going to confess about what she did years ago.

Epiphany

The most shocking moment of the story is the last sentence, ‘‘I had Barbara.’’ To Mrs. Slade, it is the most sudden life-changing moment that she would never forget. She always thinks she is better than Mrs. Ansley except that she thinks Barbara is the daughter that she wants. But now, the daughter she wants is the daughter of her husband, she loses the war to Mrs. Ansley completely. She thinks that Mrs. Ansley doesn’t have anything but a fake letter, but she has more than that but Delphin’s daughter.