YOU SAID:

My teacher said to me I'm a failure, that I'll never amount to anything.

INTO JAPANESE

私の先生は私には失敗だと言いました。

BACK INTO ENGLISH

My teacher told me it was a failure.

INTO JAPANESE

失敗だった

BACK INTO ENGLISH

It was a failure

INTO JAPANESE

失敗だった

BACK INTO ENGLISH

It was a failure