To Jesus is literally “to him.” Good News Translation makes the pronominal reference explicit.

This woman would have been a married woman, because according to Jewish Law adultery had to do with the unfaithfulness of the wife. An unmarried woman who had sexual relations with a married man was not considered an adulteress. In the ancient world the woman was looked upon as the property of her husband, and so originally the basic sin in adultery was the sin against the woman’s husband. Her sin was that she had allowed herself to be used by another man.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .