It is still a divorce. As a Catholic, the Catholic Church have a practice of allowing prominent members of the society to annul marriages instead of divorce. A case in point, Joe Kennedy Jr. (Robert Kennedy's son) married 12 years & two children, had his marriage annulled; Rudy Juliani's first 14 year marriage annulled; John Kerry's first 18 year marriage & two children annulled.
Yes she was divorce and married in a civil cermoney. But as a Catholic she had had the first marriage annulled...