On Caesar’s side of the battle, we find Caesar confident that he will be victorious.
He instructs his men of the following: he wants Antony taken alive, and he announces that the end of this battle (presumably his victory) will bring a time of universal peace.
Caesar instructs Agrippa to put the defectors from Antony’s army on the front line—he hopes Antony’s morale will be hurt by having to face his own deserting men.
All head out for some more planning, leaving Enobarbus by himself. He notes privately that Caesar has a strange sense of justice; Alexas, on an errand for Antony, ended up persuading King Herod to join Caesar’s side (it’s unclear what exactly went down here), but regardless, Caesar had Alexas killed for it. Other cases are clearer: all the others who have deserted Antony have gained employment with Caesar, but lost their honor in doing so.
Just as Enobarbus is deciding to be really ashamed of himself for his desertion, one of Caesar’s soldier’s announces the arrival of a messenger from Antony. The man bears Antony’s good tidings to Enobarbus and the treasure Enobarbus left behind, plus a little more that Antony added on.
Enobarbus is shocked and now even more ashamed of his desertion. He’s sure his thoughts will kill him, as he certainly can't bear to fight against Antony.
He hopes to die in a ditch, which he imagines is the only end fitting the miserable lowness of his recent actions.