YOU SAID:

once i ate a mouse and it was gross

INTO JAPANESE

一度マウスを食べたら、それはひどかった

BACK INTO ENGLISH

Once I ate a mouse it was terrible

INTO JAPANESE

マウスを食べたらひどかった

BACK INTO ENGLISH

It was terrible to eat a mouse

INTO JAPANESE

マウスを食べるのはひどかった

BACK INTO ENGLISH

It was terrible to eat a mouse