[SaltyJoe]

Don't forget that Cleopatra was RICH (there was a story of her dissolving a priceless red pearl in a glass of wine to prove that she'll throw the most lavish of feasts).

Antony needed someone to bankroll his ambition. Maybe he dumped his wife the same way that Kerry dumped his 1st wife for a bigger bank account. I've also heard that Cleopatra was just as power hungry and wanted her child sired by a Roman to become a Roman emperor. Antony was just the guy to do it. They were made for each others' downfall. Perhaps that's also why they probably had genuine feelings for each other in spite of their incredible selfishness (similar to Bill and Hillary?).

[The Great Yazoo]

Before her dailiance with Mark Antony, Cleo had already been impregnated by Julius Caesar, who acknowledged Cleo's son as his own (even Caesar couldn't get his wife to allow him to marry Cleo, although he considered passing a law that would allow him to marry Cleo notwithstanding his wife's objection).

[steve-b]

I've also heard that Cleopatra was just as power hungry and wanted her child sired by a Roman to become a Roman emperor.

Strictly speaking, the position of "emperor" did not yet exist. However, the Republic had broken down into alternating dictatorship and chaos, and the title of "imperator" (army commander) was usually associated, for obvious reasons, with whoever was dictator at the moment. It became the definitive title of Augustus and his successors (they took all sorts of Republican offices to maintain the pretence that the institutions of the Republic still existed), leading to the modern term "emperor".