Honestly, you should be talking to a professional, not random strangers on the internet.

Asking random strangers is an open invitation for bad advice, like the person who said this is because of what you did or didn't teach him.

Your son is still young enough that maybe you can get some help before he actually acts on the words you overheard. But you're not going to do that with advice from people unqualified to give that kind of advice.