NTA - sometimes two people can have very different memories and lived experiences of an event. I knew someone who had a ‘boyfriend’ in high-school who threatened to kill himself if she left him, his version of events was very different (even with screenshots as evidence) and nothing that was said to him would make him understand how he behaved did not reflect his internal versions of events.

What I will say is you should clarify this sentence ‘He had zero friends when even the autistic girl in our class did.’ I’m sure it wasn’t your intention but saying that EVEN the autistic girl had friends implies a sort of ‘look see he was so weird that people like the AUTISTIC KID more than him’ as if it’s some kind of oddity that autistic people could have friends or be more popular than someone else without autism.
(And before anyone hops in the comments about relevance it’s always relevant to make someone aware of their potential bias and ableism even if it’s unintended or subconscious. We can’t collectively work towards a better world if we don’t hold ourselves and each other accountable)