I am so confused about this fake, two faced behavior. This is the reason I stay away from most people.
Yes, it really does seem as though fake two-faced behaviour is actually normal; I have a feeling most people don't even fully realize they're behaving in that fashion, or else maybe because they see all the other normal people doing behaving in that fashion it doesn't occur to them to question whether they ought to be doing likewise.
In some instances fake two-faced behaviour even constitutes good manners,
e.g. saying, "Good to see you!" when actually it isn't. Again, maybe this to some extent legitimizes fake two-faced behaviour.
Typically, to those of us on the Spectrum, fake two-faced behaviour simply seems illogical.
Another possibility in the school situation you've described is that someone was genuinely keen to assist you in the context of the classroom, then wanted to "save face" by joining in the general mockery or criticism afterwards. If a load of people are running somebody down, an insecure person may wish to jump on that bandwagon in order to "fit in", which is a sad sign as far as that person goes, but meanwhile you end up suffering as a result.
But try not to give up on people altogether, because there actually
are a few genuine & good people out there. They will always be pretty rare, throughout anyone's life, but you're not even going to meet them if you give up on the whole of the human race.
I must admit I tend to shy away from people myself, but I try to keep a little flicker of hope going. I don't think I've yet met all the people I'd like to meet, so clearly I have to force myself to carry on engaging with the human race if I'm going to meet any more people that I'll actually get pleasure from knowing.
Actually, I think in the 60s and 70s what was considered bullies what someone who took your lunch money or pushed you into your lockers. And we grew up with the phrase "sticks and stones can break my bones but words can never hurt me."
This is true,
i.e. that "bullying" only used to mean
physical bullying, but even as a young & weeping little boy at primary school in the 1970s, I
knew there was something fundamentally mendacious about the old "...but words will never hurt me" gag, which the indolent teachers would try to fob me off with
every damned breaktime! Psychological bullying can leave deeper & longer-lasting scars.
At the risk of citing a somewhat extreme example, recently I heard an interview on the B.B.C. with some guy who'd been interrogated by the old East German secret police. They used no physical violence, he said: they wore him down & broke him & got their answers purely by psychological torture.