The best summary of this monologue is:
Antony sends his servant to respectfully tell Brutus that Antony loves and honors him, as he did Caesar. Then the servant says that if Antony can safely come and inquire about Caesar’s death, then Antony will be loyal to Brutus.
As it is summarized, Antony wanted to tell Brutus how magnanimous, wise, brave, and honorable he was to him, and used his servant as a messenger to do so. He also claimed the same thoughts or feelings regarding Caesar. In this way, he promises faithfulness to Brutus given that it will be safe for him to pay Brutus a visit in order to hear the story of why he commited such murder.
