Advertisement - Members don't see this ad
Yes but did you make it clear you would report him. This is effectively ruining someone's life. So you have to be clear, not vague.
It is not -- in any way -- the poster's responsibility to protect the cheater's life. He/she is not obligated to warn the cheater. Clearly the cheater doesn't give a damn about other people in the class, given his response when the OP told him another classmate failed. It's no one's responsibility to look out for his best interest.