As a renowned lifeguard struggles with his wife’s suicide, his world is in shambles when he discovers that her rapist is a family member.

Cheers.

I would probably say, "his world turns to shambles"

Also, what must the lifeguard do when he discovers the family member is a rapist? (That is the story)
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"After he discovers his deceased wife's rapist is a close family member, a renowned lifeguard must..."

(Not sure what goes after that)
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Sorry there wasn't much to go on. Good luck with this!