She felt as if the thing deserved an answer, and consequently decided that she would write and let him know that she knew of his married state and was justly incensed at his deception.

She would tell him that it was all over between them.
At her room, the wording of this missive occupied her for some time, for she fell to the task at once.

It was most difficult.
"You do not need to have me explain why I did not meet you," she wrote in part.

"How could you deceive me so?
You cannot expect me to have anything more to do with you.

I wouldn't under any circumstances.