YOU SAID:

I'm so sorry it was entirely my mistake

INTO JAPANESE

完全に私のミスでした、本当にごめんなさい

BACK INTO ENGLISH

It was completely my mistake, I'm really sorry.

INTO JAPANESE

完全に私のミスでした、本当に申し訳ありませんでした。

BACK INTO ENGLISH

It was completely my mistake, and I am truly sorry.

INTO JAPANESE

完全に私のミスであり、誠に申し訳ございませんでした。

BACK INTO ENGLISH

It was completely my mistake and I am truly sorry.

INTO JAPANESE

完全に私のミスであり、誠に申し訳ございませんでした。

BACK INTO ENGLISH

It was completely my mistake and I am truly sorry.