Some thoughts. First, when you set a boundary, do an intervention, impose "tough love," the first reaction may be anger. In this case, you can't work on the relationship until that anger is processed. Second, I'm not buying that TKD should come before your marriage and be an exception to your boundaries. They can go to different classes, or even different schools, if necessary. Certainly, your son should not be in the same room as the other man.
Maybe I'm not clear on the facts, but that is just my impression.
