Was it really, "Et tu Brute!"?

According to the Roman historian, Suetonius (Gaius Suetonius Tranquillus, c. 69-c. 140A.D.): "When they saw that Caesar had settled in his place, the conspirators stood around him as if to do him honor, and immediately Tullius Cimber, who had taken the lead, stepped closer as if to make some request, When Caesar seemed to take offense, and with a gesture put him off until another time, Cimber caught hold of his toga at both shoulders. At this Caesar cried out, ‘This is violence!', whereupon one of the two Cascas attacked him frontally, wounding him a little beneath the throat. …And so he was stabbed with three and twenty wounds, having uttered no word save one groan upon the first thrust; some have written, however, that as Marcus Brutus came running upon him, he cried in Greek, kai su, teknon, ‘And thou, my son?'"

In an earlier account by Plutarch (Greek, Ploutarchos, c. A.D. 46-A.D. c. 120; Greek historian, biographer and philosopher), Caesar said nothing, but only pulled his toga over his head.

Included in Shakespeare's play, Julius Caesar, in which Caesar's last words were expressed by his shock as Brutus (supposedly Caesar's trusted ally) stabbed him after the other assasins had already mortally wounded him.

This quotation reflects Shakespeare's version of the death of Caesar. Now, Et tu Brute! has become the classic recognition of betrayal by a trusted friend.