Melania got a green card thru marriage and it was not Donald Trump

Melania and Trump

According to NY Daily News, Melania Trump got her green card through marriage. But then Donald Trump says that she was never married before. Was the marriage just for papers? If Donald claims she was never married before but she got her green card through a marriage before he met her, then how can they legally get married without a divorce. This story raises more questions than answers.
http://www.nydailynews.com/news/politics/melania-marriage-green-card-4-years-wedding-trump-article-1.2741180

How in the world can Donald Trump hate immigrants if his own wife was an illegal alien? This makes no sense to me. If Donald married a married woman, that is bigamy.

The article says that Attorney Michael Wildes "clammed up" during questioning. It is still not clear to me what exactly Mr. Wildes did for Melania or Donald. And I sat almost 44 months for immigration fraud. I wonder if her marriage was just for papers and I wonder who was her lawyer who represented that case.