and; and what’s more; emphasis~

Explanation of

ボク、 本当ほんとうは1にん 夏休なつやすみのここにいるってまったとき...
ちょっぴりこわかったんだ。
だって、おじちゃんのかおおぼえてなかったとおいっていてたから。

When It was decided that I was going to stay here for the summer holidays by myself...
I was a little bit scared.
‘Cause, I couldn’t even remember Granpa’s face, and I hear it was far away...