He didn't admit it Faulk because he refuses to call it what it is, a emotional affair, and he refuses to stop the lessons.
His lips are moving but it's just hot air coming out.
Your ds is picking up on the atmosphere. Children are very sensitive to emotions. Remember, your ds was aware of the affair before you were. He was the one who told you about it.
I work with children in school and one of the things that comes up time and time again is parental separation. The separation itself is not the most difficult time for the child.
The time that they find hardest to cope with is the time leading up to the separation. This is a time of high anxiety, great stress and emotional upheaval.
The child is so uncertain of each day, they live in a kind of limbo, just trying not to rock the boat or do anything that might tip the fragile balance of their parents' relationship. Of course, it's nothing to do with the child but they don't know that.
The longer this phase lasts, the harder it is for the child. They are often unsettled at school, become withdrawn, or tearful, or possibly act out their anxieties in unwanted behaviour. It's all a normal reaction.
Once the parents separate, the child starts to settle down again, especially if routines are put into place fairly quickly. One of the parents moves out of the family home and the atmosphere clears almost instantly. The child can relax because the tension is broken. Even if it's not what the child would have chosen, sometimes, quite often in fact, separation of the parents is the best choice for the wellbeing of the child.
Anyway, I'm only telling you this in case you aren't aware of how a long, drawn out affair like this can affect the children.