Don't feel bad. He's old enough to handle and be included in exposure.
YOu DO need to give him some direction on how you would like him to handle himself now that he knows...
Just have your son give his father a hug and tell him he's proud of him for going.
He could just as easily see the facebook stuff himself... kids have the time and energy to read that stuff all day.
I am shocked he would put stuff on facebook right in the open where his kids might see it.
Your son can HELP motivate his father. I think he should start motivating him as above and do what he can to add support to his father rebuilding the marriage.
He's old enough to be involved Sunny
phil McGraw did an affair intervention on national tv and had a 14 year old daughter speaking up and involved... and I agree with him that 14 is old enough to warrant their input at that point. It's unfortunate, but excluding them and making decisions without them is unfortunate too.
They will be glad one day they were respected as an adult and give a chance to help save the marraige.