I've been reading some of the books that have come out recently about Jesus, saying maybe He was married or Judas was His most faithful disciple, and things like that. How do we know Jesus was really like the Bible says He was? These books might be right instead of the Bible. — K.McC.
Elsewhere in your letter, you mention some of the books you've been reading—and most of them, I noticed, are fiction. In other words, they are simply the product of an author's imagination, and you shouldn't take them as fact.
Others you mention are based on documents written hundreds of years after the time of Jesus—and they too have no basis in fact. They came originally from groups that rejected the teachings of Jesus, and were invented solely to support their ideas about God. Interestingly, when the Roman authorities set out to persecute Christians they didn't bother these groups, because even they knew they didn't represent true Christianity.
The Gospels alone are reliable—and one reason we can trust them is because they were written while thousands of people were still alive who had heard Jesus teach and witnessed His miracles. If the Gospel writers had distorted the facts, these people would have complained! But they didn't, because their record was right.
We can trust the Bible also because God watched over its writing: "For prophecy never had its origin in the will of man, but men spoke from God as they were carried along by the Holy Spirit" (2 Peter 1:21). Make the Bible part of your reading. You'll not only learn about Christ, but you'll discover God loves you and can change you if you will open your life to Christ.