You know him better than anybody, but not better than he knows himself. This I think is true of everyone, A or not.
Did he belly laugh? You said you busted out laughing, did he? There's a noticeable difference between a real laugh and a fake one.
Were his eyes shining? You know the stuff that can't be faked.
All that aside though, I think you feel betrayed because you thought you were both having good times.
I sure can understand feeling betrayed in those circumstances.
Is he "faking it until he makes it" ?
I would simply say that I had a really good time, and was sorry he didn't think the times were as good. Maybe that will plant a seed in his head to reconsider whether those were actually fun times after all.
The rest is his baggage to work through.