How did Cedric betray Crispin?

Cedric betrayed Crispin by revealing Crispin's identity as the son of a nobleman, which put him at risk. Despite their earlier camaraderie, Cedric's actions were driven by self-interest and fear of the repercussions of harboring a fugitive. This betrayal ultimately led to significant consequences for Crispin, as it compromised his safety and freedom.