Father, help this man to deal with his pain. Draw him close to you that he may be comforted. Father...let him know that his prayer of forgiveness has been heard by the Lord, and he has been forgiven. While I do not know the circumstances of his wife's moving on...I would encourage him to pray that she also be draw closer to you Father that you might mend up her heart and soften it. I sincerely hope that the she will do so.
I agree with Ashley that rather than giving up this man speak life to his marriage and to the healing of wounds in his wife. In Jesus name...Amen!

May God bless you abundantly.