Why did Cleopatra want to kill herself?

Why does anyone kill themselves? Ancient Egypt was dying, a once-glorious empire losing a war with Octavian (later the emperor Augustus). Her husband (slash lover, because the marriage is doubted and was recognized only in Egypt) Mark Anthony committed suicide and died in her arms just days earlier, and she was being kept captive in Alexandria by Octavian. She was most likely going to be paraded in the streets of Rome, bound by golden shackles and utterly humiliated. But Cleopatra did not plan to lose her dignity. She was a proud woman, but not in a vain way: a regal way. She was born royalty, and would die as one. And she did.