If you ever decide to end your affair, I will be here to forgive you.
------I would take out "ever" and change "will be here to" to "can".
You know this is tearing me up inside, I cannot make you stop what you are doing. I can only pray that you will.
------She may see this as guilting her and may get mad, or she may just think "he has no clue"...either way, it probably won't affect her the way you want it to.
You remain in my prayers. For our last night together under this roof as a family come up to bed and let me hold you one more time before you leave.
------I don't disagree with this. But, like Karen pointed out, be prepared for her to say no.