As a parent, how would you handle learning your child bullied someone to suicide?

Too many cases of students committing suicide due to getting bullied are happening at schools. So what would you do in this scenario:

You're watching the news of a student that used to go to your child's school just committed suicide. He/she was getting bullied so much. The bullies would go as far as saying they're better dead because no one needs them. Weeks later, the student pulls the trigger, leaving a suicide note.

Then later on, you find out your child was one of the main bullies that resulted in that student's suicide. Your child returns home like nothing ever happened and doesn't seem like he/she cares. What would you do in that case?

This is a real life case of a 13 year-old committing suicide after his birthday as a result of getting bullied:

https://people.com/new-hampshire-boy-dies-by-suicide-after-13th-birthday-amid-bullying-concerns-family-says-11931694

As a parent, how would you handle learning your child bullied someone to suicide?
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