I think Chuck's son has clearly set some boundaries in his own life.

He won't deal with his father unless certain conditions are met.
He will deal with whatever consequences his father chooses as a result of setting those consequences, and has decided that includes not ever dealing with his father again.

I think that is pretty brave for a 19 year old.

Where I disagree with the young man is that he wants all of this in writing. I think he and his father need to talk in person. I think the relationship between parent and child deserves that kind of intimate opportunity, particularly with this quite devastating event that has occurred.

Chuck, what I might suggest is for you to go to a family counselor, explain what has happened, and ask for an appointment where you and your son can sit down in a controlled situation with the counselor where you all can talk through what your son needs to say for at least one or two initial times. It might help your son feel safer, and set the forum for a more productive time together for repairing your family. You might call your son and ask him if this would be something he would be interested in doing, because he may buy into it if he feels part of the decision to do it in the first place. ASK him if he thinks it would be a better idea to talk "just you two", or if he thinks it would be more productive if you went to counseling first and then he were to join you to go over his questions at a session or two in "a more structured environment".

See what he thinks. Follow his choice. He is struggling, and it is important to respect that he wants to repair it - and is looking for a way to do this with strength (hence the ultimatum) and still protect mom, and keep you....somehow....