Why has Van Helsing waited until now to begin to explain the truth behind Lucy's death?

Until now Van Helsing really doesn't have an answer to why Lucy was the victim. He had no words of comfort. The coincidence of Dracula attacking Lucy, who happened to be Mina's best friend, is an argument that fate or providence has a strong hand in the novel's events. The theme of fate or God's hand in events is touched on throughout the novel. Van Helsing later states that Mina was fashioned by God for some great purpose, and the great coincidence of Jonathan's connection to Lucy seems too unlikely to be pure chance.