Answer:My wife had three children out of wedlock before we got married and has just informed me that she had sex with someone else during our marriage. I think I have the right of divorce, but my question is, what should I do. It appears to me that she cannot be faithful.
"He said to them, "Moses, because of the hardness of your hearts, permitted you to divorce your wives, but from the beginning it was not so. And I say to you, whoever divorces his wife, except for sexual immorality, and marries another, commits adultery; and whoever marries her who is divorced commits adultery." " (Matthew 19:8-9).
Assuming that you have been faithful to your marriage vows, you are correct that Jesus' teaching does allow you to divorce your wife. After the divorce, you could remarry again without committing adultery. However, please remember that it is an allowance and not a requirement. Only you can decide whether it is worth attempting to rescue your wife and your marriage.
If you do choose to leave and seek another wife, I want you to think carefully about the kind of woman you select. You've noted that your wife already had three children prior to marriage. I'm assuming they were produced by other men. Prior to entering into a covenant with the woman, you already knew that she treated sex casually. If she had multiple partners, you knew that she was unable to remain committed even without vows before God. What made you think that her behavior would change? Her current behavior is just an extension of her behavior prior to your marriage. If you look for another wife, find one made of better material.