When to use ひらがな vs カタカナ
I always thought that ひらがな was used to write Japanese words, and カタカナ is used to write 外来語.
But in a message, a native Japanese speaker wrote "ゴメンね”. Using both hiragana and katakana in one word, and also using mainly katakana for a Japanese word (It was "sorry", right?)
I'm confused what the rules for using hiragana and katakana are, can anyone explain it to me please?