Gov. Chris Christie on Thursday apologized to his constituents and said he was “embarrassed and humiliated” by his staff, one day after emails and text messages revealed his administration may have closed highway lanes to exact political retribution. Christie also said he was firing Deputy Chief of Staff Bridget Anne Kelly, “because she lied to me.” Kelly is the latest casualty in a widening scandal that threatens to upend Christie’s second term and likely run for president in 2016. Documents show she arranged traffic jams to punish the mayor, who didn’t endorse Christie for re-election. The revelations thrust a regional transportation issue into a national conversation raising new questions about the ambitious governor’s leadership on the eve of a second term designed to jumpstart his road to the White House. The messages do not directly implicate Christie, but they contradicted his assertions that the closings were not punitive and that his staff was not involved. Christie acknowledged Thursday that was a lie, because his staff didn’t tell him what they had done.