。
I'm really sorry, man.
Literal
Truly sorry [insistence-よ].
ゴメン (ごめん), here written in katakana for casual emphasis (often a childlike or stylized effect), is the plain-form apology — more casual than すみません, typically between friends or close family. Final よ delivers it emphatically, almost imploringly. Writing normally-hiragana words in katakana is a stylistic choice that adds visual punch.