There are a couple of things to consider here. If she was married and her spouse is still alive and their marriage has not been annulled, then for practical purposes she is not available for you to date. You must consider her a married woman, regardless of whether the state recognizes her as legally married or whether she no longer lives with her husband. When a person is married, he or she is married until death. Only if the Church determines that the presumed marriage was never valid can the person be considered available while the former partner still lives.
This is why Jesus said, ‘‘Whoever divorces his wife and mar- ries another, commits adultery against her’’ (Mark 10:11). This includes doing anything with a divorced person that you would not do with a married person. This is a difficult saying, but it came from the mouth of the Lord.