It’s not terrible. His denial is going to be so bad based on what you’ve quoted from him and you have not asked for specific action in your letter other that quitting, which he may do a few times a week when he sees the kids who knows. Dr. H has specific experience in this and I think could help you with a letter that would help you protect your family better.

Me 40, OD 18 and YD 13
Married 15 years, Divorced 10/2010