YOU SAID:

party is ruined because YOU ARE UGLY.

INTO JAPANESE

あなたが醜いので、パーティーは台無しです。

BACK INTO ENGLISH

Because you are ugly, the party is spoiled.

INTO JAPANESE

あなたは醜いので、パーティーは損なわれます。

BACK INTO ENGLISH

You are ugly, so the party will be hurt.

INTO JAPANESE

あなたは醜いので、パーティーは傷つくでしょう。

BACK INTO ENGLISH

You are ugly, so the party will be hurt.