Newmark was duped by a male reporter posing as a young, blonde, female, PR worker who had hoped to meet him at the Tory conference. In the lead up, they had communicated online and become friendly, to the point that they sent explicit photos to each other. Obviously, those from the reporter were false, but Newmark exposed his stupidity, as it were, by sending his bare details. In addition to being an MP and Minister, he's married with five children. When the newspaper was ready to publish the story, he resigned.
Yes, Newmark was stupid and was made a fool of, but was he right to resign? It depends on the reason. Sending explicit photos to someone who has privately asked for them is hardly a crime. In these days of hacking and revenge exposure, it isn't a wise thing to do, especially if you're a public figure, but it's really just being foolish. Further, it's probable that his wife wasn't too pleased at the revelation, but that's a private matter.
Newark's big mistake was to be hoodwinked into thinking that a young blonde would be so interested in a 56 year old man, and he was smitten. It's not a new story, it's happened countless times before. So often, gullible men have been taken in by the charms of a pretty woman and have fallen, not on their sword, but their penis. Numerous careers and personal relationships have been shattered.
The reason why Newmark was right to resign was because of poor judgement. He was in a position of responsibility and trusted by his party and electorate, but he let them down. The Sunday Mirror may feel proud of themselves; nevertheless, I think their actions were possibly illegal and certainly underhand and unnecessary, playing into the weakness of a man for political purposes. Newmark, however, should have maintained the standards expected of someone in his position, and he didn't.