Can someone explain the new batman movie ending?I'm a bit skeptical.?

Okay he said he had to be the bad guy? Whats up with that?

Harvey Dent had a reputation as a great, heroic common man who was a sort of symbol of justice for the citizens of Gotham. Batman, while he is clearly the hero to us as an audience, does not have such a reputation among the city's residents. All the kids, it seems, and everyone he helps really like him, but the police and other city authorities are always saying that he's a lawless vigilante.

The reason he said that he is the bad guy is because he decided that he would take the blame for the deaths of the people that Harvey Dent killed after becoming Two-Face, as well as Harvey Dent's death. He figured it would be better for the citizens of Gotham to mistrust him, as a questionable vigilante who kills people for seemingly no reason and follows nobody's rules, than to see that Harvey Dent, the beacon of truth and justice, had fallen prey to rage and destruction and hostility against his fellow man.

Harvey Dent's memorial service was that of a hero. As he said "You either die a hero, or live long enough to see yourself become the villain." He became the villain, but preserving his image as a hero who died for the cause was very important in keeping the city's hopes alive, and to keep it from returning to what it was before.