How can a U.S. citizen spouse annul a marriage with a temporary green card holder spouse when there are evidence that the marriage was a fraud?

The couple met online approximately three years ago. They have not been in touch until summer of 2013. In late Sept 2013 they got engaged and got a ceremony and marriage certificate in Dec 2013. The husband is a US citizen while the wife at the time of marriage was on student visa. Her visa was supposed to expire in the spring of 2014. In April 2014 the couple had another wedding ceremony and reception because the bride's parents didn't have a visa to visit the US back in Dec 2013. Between the summer of 2013 and August 2014 the couple lived in two different states, 7.5-hour drive away. They had an interview with an USCIS officer in Aug 2014, days after the wife moved in with her husband. A temporary green card was issued to the wife. Then the husband said she started to mentally and monetarily abuse him more severely compared to before getting a green card. He tried to commit suicide but was rescued. Now he's still alive he suspects the marriage was her plot to obtain US citizenship.