I think you're right and it is the verb form rather than the adjective. If we change the sentence to active voice it would be: The news of Annabel's suicide shattered the family. If you change it slightly, shattered becomes an adjective: The family were shattered because of Annabel's suicide. It's not always clear whether it's the verb (action) or the adjective (state), though. The shop was closed at 8. - Did someone close it at this time or had it been closed before. Compare this to the irregular adjective 'open': The shop was opened at 8. - verb/action The shop was opened at 8. - adjective/state

It’s an adjective derived from the verb ‘shatter’, meaning ‘break into pieces’, ‘destroy’ ; for example, a glass window or a ceramic vase or plate will be shattered if struck by a hard object or dropped on a hard surface. The word is used metaphorically to suggest psychological or emotional devastation caused by an event. The past participle, used in passive mode, as you note, also functions as an adjective. ‘The shattered vase was put together again by the museum staff.’ In your example it can be seen more clearly using the synonym ‘devastated’ : ‘The devastated family reacted to Annabel’s suicide by coming closer together.’

In active voice the sentence becomes "The news of her suicide shattered the family". Past participles by their very nature create unanswered questions, even without passive voice. For example, the sentence "I found a buried treasure in the garden" uses active voice but leaves unanswered the question: "Who buried the treasure?" So past participles introduce an element of passivity whether the voice is active or passive.

Thank you! :) 🙏🏻