I am praying for you.. I would write the letter. Then set it side before sending it, pray on it, leave it in the bible while you are out or sleeping. I wrote my husband a letter in 2 months ago and have not given it to him yet, just not felt it is the right time. This gives you time to reflect, pray and not act in a rushed manner. It helps to read it aloud to someone you trust and value their opinion. I pray to the Lord that He shows you the words to use and guides you to be able to express His love for you and your wife through this letter. Lord please guide this man to be able to everything he can unto Your will. Bless all of our hurting marriages. Please Lord, guide and lead our spouses who are lost, and carry them through their weaknesses. At times, their weaknesses are leading them the wrong direction. Even if they are not choosing the right path, Lord please see their hearts and see their weaknesses and help them. Lead them to the people you want them to be.
Amen.