I have a friend and I am trying to teach my friend the truth. I found out that he is in an adulterous relationship. His wife was married before but for only one year. The marriage did not end because of fornication. She is now married to my friend. They have been married 25 years. Is it true that he would have to leave his wife in order to be in a right relationship with God?
Let me change the terms and see if the solution becomes clearer: "I have a friend who once had an honest job, but he quit and is now a jewelry thief. He has been supporting his family for the last 25 years with the money he has gained from stealing jewels. Do you mean to tell me that I have to tell him he can no longer support his family in this manner if he wants to be a Christian?"
The length of time a sin has been committed does not change whether something is right or wrong. The fact that good comes as a result of sin doesn't make the sin right or wrong. The problem with adultery is that we want to excuse it. This is why our Lord said, "All cannot accept this saying, but only those to whom it has been given" (Matthew 19:10).