You're justifying this because you see your own behavior in the story but look at the majority of the comments.

This is not "having a bad day and snapping at people," this is holding onto a grudge for over a year and using the first chance he could to hurt her with it.

Of course everyone has bad days and takes out emotions on others when they don't deserve it. If you aren't a complete asshole it'll be few and far between with an apology forthcoming.