It's crazy how you're relaying what I would also consider to be a realistic and most probable explanation for what happened. Yet you're getting downvoted because people don't want to hear the fact people talk behind other people's backs. It is literally ubiquitous and it's a common way of getting over a problem. Good friends know the difference between talking shit to feel better and actually hating someone.

Speaking of which, I can't stand the white knighting happening in this thread. "LOL I AM A GUY AND I WULD NEVER DEW DAT." Yeah, no shit, because you're mr. perfect. It's not only entirely anecdotal to say that but flaws are hard to fix because they're harder to see a solution, let alone the problem. You might not realize you have a bad habit of talking shit when you're angry until it backfires like in OP's story.

The solution? Talk to him and learn the truth. If he can't be friends anymore than it's over. OP can't be mad at him for choosing not to be friends because he can't handle his feelings if they aren't reciprocated. It was just a huge waste of his time to not try dating her years prior. He could have very well broken up with his girlfriend after thinking OP would definitely date him after all these years and that's why it hurt when it didn't work. She could have said a lot of things he misinterpreted thusly being "lead on". I'm guessing that was really the root of the problem... he's had feelings the entire time and tried to cash in only to realize it was never going to happen. That's enough to stir anyone up.

But, you know, it's two x chromosomes. It's easier to just assume the guy is a rampant rapist dickhead incapable of feelings than to actually wonder if someone posting something anonymously on the internet is giving us all the facts.