Jeff, there is NEVER any justification for sin! You are now an adulterer, too! You need to repent, change your attitude, or you are going to spend the rest of your life jumping from one tangled relationship to another.
God does not want you to leave the wife of your youth, even if she has betrayed you! Praying you break off with this new woman, and that you can get the marriage counseling you so desperately need.
Love is NOT a feeling. Marriage is a commitment that you have now also despoiled.
“Did he not make them one, with a portion of the Spirit in their union? And what was the one God seeking? Godly offspring. So guard yourselves in your spirit, and let none of you be faithless to the wife of your youth. For the man who does not love his wife but divorces her, says the Lord, the God of Israel, covers his garment with violence, says the Lord of hosts. So guard yourselves in your spirit, and do not be faithless.” Mal. 2:15-16
God will judge you on what you have done, not on what your wife has done. So please get your accounts straight before God.