After that, Pompey made a royal screw-up and lost a major decisive battle to Caesar and his much much smaller army. Pompey then had to escape the nation, and he figured that the safest place would be Egypt, where reigned one of the Ptolemies, who at the time was trying to steal the throne from his sister Cleopatra and keep it out of the hands of his other sister whose name doesn't occur to me right now. Ptolemy's advisor (whose name i also can't remember) had heard of Pompey's bad standing with Caesar, and killed the general when he arrived in Cairo. This disgusted and disappointed Caesar, who wanted to kill Pompey with his own hands. Caesar went back to Rome and had Pompey buried formally, and that spelt the true end of the Triumvirate.
And i might mention that before becoming triumvirs, all three men were pretty powerful. Crassus was the richest man in Rome, Pompey was an esteemed war hero, and Caesar was Pontifex Maximus i think.
Also, fibber, i think "crossing the rubicon" is a metaphor or whatever you want to call it meaning "passing the point of no return", as per what vito just explarned.
...Now, uh, why are we talking about this again?