Sweetbriar, They need the time to focus on themselves and the only way to do that is to leave them alone as much as possible. Keep in mind, the affair is only a symptom of the depression/mlc, just as alcohol, spending, gambling, internet, drugs, etc. If they aren't allowed to experience these things full throttle, they won't get to the point of working through their pain and hitting bottom.
Oh, they do have time to focus on their issues, especially at night, when it's quiet and there is nothing to keep them busy. There will be times when he will zone out and sit around thinking about things and the ow and other self-medications can only work for so long before he goes searching for something new. The novelty does wear off at some point for each of them.
If we are in contact w/them or trying to get them to interact w/us, as well as "expecting" them to act like adults and face their responsibilities on the home front, they can't focus on facing their own issues and then healing.
Your h is not only caught up in his affair (lust) right now, but his new found freedom w/no responsibilities. He's a teenager all over again and he's wiser this time around because he knows what he can get away w/and has the money to do so. Many of them are not as wise as they should be because of STDs and using protection...they tend to forget about that aspect of things.
BTW, they do tend to compartmentalize all aspects of their lives right now and that's how they manage to function in the "real" world.
You may want to read the thread "Why They Run Away". It will provide you w/some insight into their mlc minds.
I'll take a look at your thread and provide you w/my opinion.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.