The last time Sitora Yusufiy walked into the house she once shared with her ex-husband, she did so with a police escort. When she first met Omar Mateen, he had been charming and fun-loving. But, after only a few months of marriage, she began to fear him. He began to isolate her from her family and with very little warning he would become enraged and aggressive. Related ArticlesJune 14, 2016 Orlando gunman had been seen on gay dating apps, at nightclub before shooting June 14, 2016 Possible motives emerge for club gunman as Orlando mourns June 14, 2016 Fiery Trump, sober Clinton at odds over Orlando attack June 14, 2016 Victim vignettes: A look at some of those killed in the Orlando shooting June 13, 2016 Vigil for those murdered in Orlando draws strong, united crowd in Denver “He had a very good way of masking that side of him,” Yusufiy said. Yusufiy, who was briefly married to Mateen in 2009, has offered some of the few insights into the man who committed the worst mass shooting in United States history.