YOU SAID:

They are laughing at me not with me.

INTO JAPANESE

彼らは私と一緒にではなく、私を笑っている。

BACK INTO ENGLISH

They are not laughing at me, not with me.

INTO JAPANESE

彼らは私と一緒にではなく、私を笑っていません。

BACK INTO ENGLISH

They are not with me, they are not laughing at me.

INTO JAPANESE

彼らは私と一緒ではない、彼らは私を笑っていない。

BACK INTO ENGLISH

They are not with me, they are not laughing at me.