あのとき

at that time

→ あの
phrase Uncommon #16,261
at that time Refers to a specific time in the past, often one already known from context. It can appear in regretful or hypothetical statements about what happened or did not happen then.
JA: あのときは何も分からなかった。
EN: I didn't understand anything at that time.

あのとき君が話をしていた女性は私の妹です

The woman you were talking to at that time is my younger sister.

あのときリアル死ぬかと思った

I honestly thought I was going to die then.

あのとき彼女と一緒だったらよかったのに

I wish I had been with her then.

私はあのとき父がいったことを決して忘れないでしょう

I will never forget what my father said then.

あのときトム電話してくれなかったら自殺してたかも

If Tom hadn't called me then, I might have killed myself.

あのとき私がした約束は有効だ

The promise I made back then is still valid.

あのときトム気持ちがようやくちょっと分かった気がする

I feel like I finally understand a little of how Tom felt back then.

あのとき彼の名前を知っていたらなあ

If only I had known his name back then.

もし私があのときその絵を買っていれば今では金持ちだっただろうに

If I had bought that painting back then, I would be rich by now.

彼があのときタバコをやめていたらこんな病気にはかかっていないかもしれないのに

If only he had quit smoking back then, he might not have gotten this sick.

あのときカメラを持っていればなあ

If only I had brought my camera then.

あのとき本当のことを話してくれたらよかったのに

I wish you had told me the truth back then.

今になってようやくトムあのとき言ってたことの意味が分かったよ

Only now do I finally understand what Tom meant back then.