YOU SAID:

i ate my cat ate the food that was a nice day

INTO JAPANESE

猫を食べていい日だった食べ物を食べた

BACK INTO ENGLISH

I ate food that was a good day to eat cats

INTO JAPANESE

猫を食べるのにいい日だった食べ物を食べました

BACK INTO ENGLISH

I ate food that was a good day to eat cats