Separator between Date and Time

Hello,

How do I add a separator of a dash or @ between the Date and Time for the events widget? I know where in the code I have to edit, but not sure how to do it:

bg-group-calendar.php - Line: 1496
$events_list .= stripslashes($event->name).'<span class="calendar-widget-date">'.date_i18n($date_format, strtotime($event->event_time)).'</span><a href="'.$url.'" title="'.__('View Event', 'groupcalendar').'">'.stripslashes($event->event_title).'</a>';

As you see I have edited a little to fit my style, I just want to know how to add this separator and it'll be great!

Cheers,
Daniel