Your son needs guidance on how you want himt o handle it. If you want himt o just be quiet about it and show pride when his father tells him he's going away for the trip that's fine.
It's best not to tell your H that yo shared info with his son right now. He's NOT emotionally stable enough to receive the news well.
And your SON may have some input here.. he may WANT you to keep it quiet too... he DOES have a right to say how HE feels about it...
It's a secret that belongs to you and your son now... you two need to communicate about it honeslty and regularly as a famly should...
When exposure happens this interesting "reverse exposure" thing happens...
Suddenly YOU and the FAMILY are in on a SECRET and the WAYWARD spouse is out of the loop... now its Y OUR turn to hide secrets from HIM... see?
And yes, he woudl be furuios.
I honestly don't think if his facebook is innocent he should be HIDING it from his KIDS... do YOU?