OP, I don't mean to be unkind when I say this.
I'm noticing that you don't seem to pick up social cues very well. I was joking when I said YABU to use such an irritating phrase. I'm really surprised to see you apologising to me. I was being facetious and frankly quite rude to you.
It also strikes me that you keep trying to apply logic to this situation. You talk about presenting an alternative viewpoint, supplying sources, etc as if the proceedings are logical, emotionless and factual.
But people react emotionally, and defensively, if you challenge them, whether they feel you're subtly undermining them or they feel totally defensive. Most people will not immediately agree and change position even if you are obviously right, but will become more defensive. It's like how two magnets can push against each other.
You question why someone keeps messaging you when you obviously don't want to engage. Because they are riled and want an argument and you're annoying them by not giving them a spat?
I think the loss of this friend is not much of a loss. I'm not criticising your viewpoint. But I think it's a bit odd that you can't see why she was pissed off.
After 4 weeks, I sent her a pm saying that I had many good friends and none of them criticised me as much as she did, that there was nothing wrong with my knowledge of my own subject and she might want to apply her own judgemental criticism to herself at times.
Can you see that this lacks understanding of the emotional side? It was never about your knowledge but about how people felt, social cues, behaviour. She was unhappy about being corrected or shown up in public, about you arguing on her page with her friends.
While I don't like the sound of this woman, I do get where she's coming from. One of my old uni friends recently disagreed with a comment a work associate made on a status of mine and I felt deeply uncomfortable and worried she was offended by his tone.
This was never about your knowledge. I find it really odd that you didn't write something like: "Look, sorry if you were annoyed or upset by what I posted. I usually think of status updates as something I can respond to, didn't mean to cause a fuss."
Apologies if I'm way off base here but do you normally have this much trouble with social cues? Have you ever been tested to see where you are on the autism spectrum?