I admire Brutus because he sacrificed it all for the good of Rome. He lost his wife during the tragedy.
His reaction is somber but calm. He reacts stoically. Brutus does not allow Portia's death to hinder him. He gets ready for battle. He is impassive about her death. He calmly prepares to meet his enemies.
On the other hand, Cassius' reaction to Portia's death is that it makes Brutus too willing to confront his enemies. Cassius suggests they wait for the enemies to come to them.
Brutus is ready to go to meet his enemies.
Cassius suggests they wait for the enemies and be rested up for war.
Brutus is eager to confront his enemies. "I have the patience to endure it now" is a quote Brutus makes upon hearing of Portia's death. Perhaps he is saying that he has nothing to live for now. War and death would be a welcome relief after losing his beloved Portia.