YOU SAID:

I already "befriended" your mom last night

INTO JAPANESE

私は昨夜あなたのお母さんとすでに「友だち」になっています

BACK INTO ENGLISH

I am already "friends" with your mother last night

INTO JAPANESE

私は昨夜あなたのお母さんとすでに「友達」です

BACK INTO ENGLISH

I was already "friends" with your mother last night.

INTO JAPANESE

私は昨夜あなたのお母さんとすでに「友達」でした。

BACK INTO ENGLISH

I was already "friends" with your mother last night.