Ok, if something didn't happen, I doubt that he would have responded to you in such an angry negative way....his action whether he admits it or not says he got caught doing something he didn't want you to notice. By acting so negative it's almost like he is bullying you into not believing what you really saw. People don't react so swearing negative if they really haven't dine something most times.

Give him his space....honestly I wouldn't want to keep a friendship like that going even if you have been friends for 10 years. A REAL friend doesn't react the way he did whether he did or didn't do what you saw in the way you saw it. Don't doubt what you saw just because he tells you to.

IMO....Let that friendship slide into a work place acquaintance. This is something you can't fix....the way he treated you was totally unacceptable & he should be the one apologizing NOT YOU.