This firmly-worded goodbye letter ends contact between two people having an affair, and can be inspiration for breaking off a liaison.
Dear {Recipient},
This will be my last contact with you and I think it best that it be in a letter so that I can say what I need to say clearly, directly, and without misinterpretation.
I have been incredibly selfish, thoughtless, and cruel. I have hurt you, my {wife/husband}, our family, and myself. I have dishonored the vows that I made to my marriage and it's time that I honored my promises. I have reconciled with {Spouse} and {he/she} has miraculously agreed to work with me to rebuild our relationship.
In order to do that, I can't see you or talk to you again. It's much too difficult and it hurts too much. You deserve to be with someone who can commit 100% to you and be in a real, open relationship. I know that you'll find someone to treat you the way you ought to be treated. I am so sorry for hurting you.
Please help me stay strong in my resolve by ceasing all contact with me from this point on. I'm sorry for all that I've done.
Sincerely,
{Sender}
