he has to get to the bottom of why he was "unhappy"
is he blaming you ?
looking for excuses to justify himself ?
having a twatty "midlife crisis" ?
feeling "confused" ?
if he just puts it down to temporary "unhappiness" but has now miraculously come to his sesnses (because he got caught...) then nothing will resolve
you will not trust him again
he will not feel that you have "moved on", he will start a feel a bit "unhappy and confused" again....
can you see the pattern here...
I think it has just hit me that the OW was drunk and he was stone cold sober
I absolutely do not think that alcohol is any excuse at all, and I am not sure why him being sober makes it worse somehow...but it does
that is fucking nasty...but I can't really articulate why...other than the fact he was very much in the driving seat, knew exactly what he was doing, and took full advantage of her at a vulnerable moment
the other thing that would absolutely make be volcanic with rage...is that people at his work knew all about it
any person who ever makes a fool of me had better be ready to deal with the consequences...OP, I suggest you dig deep for that anger and push the soft, fluffy forgiving thoughts to the back of your mind
at least until you are 110% sure about him, his motives, your own position and clocked how he behaves over the next few weeks