Who is Sylvie Cole from One Day and what is their importance?

Sylvie Cole is Dexter Mayhew's first wife. She fell in love with Dexter after his fall from fame, and sought to build a life with him. After learning she was pregnant, she and Dexter married. Soon after, the marriage dissolved when Sylvie had an affair with Callum McNeill. In the end, though they are divorced, Sylvie helps take care of Dexter, getting him to his father.