YOU SAID:

this sentence will mean the opposite of what it meant at the start when this is finished

INTO JAPANESE

この文は、これが終わると最初の意味とは逆の意味になります

BACK INTO ENGLISH

This sentence has the opposite meaning when it ends

INTO JAPANESE

この文は終わると反対の意味になります

BACK INTO ENGLISH

This sentence ends with the opposite meaning

INTO JAPANESE

この文は反対の意味で終わる

BACK INTO ENGLISH

This sentence ends with the opposite meaning