"Tu quoque" is a later tradition. According to Suetonius, who writes more than a century later but is our oldest source on this, the literal words were in greek and it was "kai su teknon?", which is literally translated as "You too son?".
Three different interpretations of these last words are mentioned in this Quarantine answer: https://www.quora.com/If-you-accept-the-premise-that-Caesars....