A faded piece of papyrus refers to Jesus' wife. (New York Times link here - but the link sometimes prompts a log in.) Just read the first paragarph of the story and, fortunately, it leads with the most important piece of information - it's from the 4th century. That's 300 years at least after Jesus ministry on earth, and centuries later than the New Testament documents were written.
The gnostic gospels were rejected by the church because they knew they weren't accounts written close to the time they report, as the New Testament documents were. The gnostic gospels date at least more than 100 years after Jesus, most of them much longer than that. They weren't considered authoritative because they were far removed from Jesus life and the authorship couldn't be traced to an eyewitness. Someone close to Jesus' life was in a much better position to report accurately about his life than someone three centuries removed.
Even if authentic, this fragment is dated way too late to take seriously. Even Karen King, the scholar who revealed the fragment cautions that.
We also don't know what kind of document the fragment is from, what kind of literature it is. There is so much unknown here and the response is way overblown.
Michael Kruger cites some key differences between the gnostic gospels and the New Testament documents.