Using 'own up' often implies a feeling of regret or embarrassment about admitting something. After the argument, she decided to own up to her harsh words.
Pro Tip 2/3
Not Instant
'Own up' suggests a delay or hesitation before admitting something, not immediate confession. He hesitated for a week before he owned up to cheating on the test.
Pro Tip 3/3
Voluntary Action
To 'own up' is usually a voluntary action; it's a personal choice to admit to something. Despite the peer pressure, she decided to own up to the mistake.