This is a scam, and it's very well known.
You are not communicating with your former student. His contact information has been hacked and a scammer is impersonating him to try to get all of his Facebook friends to send money to claim a grant of some sort that doesn't really exist. The reason he does not want you to tell anyone is because many will likely know about this scam, and then you won't send the money to him.
You can read more about this fraud here.
You want to contact Facebook about this and get your "former student's" cloned profile taken down. You can also report the scammer to the FBI at IC3.gov, their Internet Crime Complaint Center. If you wired him the thousand dollars, you should also report the fraud to your police.
Just checking in to see if you need more help or any clarification of my answer. If so, please reply here on this question thread.