You are the problem.
First there was the weird initial post where you insulted other children who have "problematic beheaviour" calling them domineering and threatening and disruptive compared to your kind, no argument, no complaints kid.
Massive "not my angel" red flags there.
Caling the mother "odd" and icy cold. Pretending that someone not wanting to hang out with you is bullying and then the dramatic "do some people just like making little kids unhappy?"
You came off very badly, straight away.
You then spent the whole thread completely ignoring the majority of messages asking you to reevaluate and take a chill pill and seizing on to the few who might agree with you.
Post after post after post. Why bother putting it in AIBU, you are absolutely determined not to listen to anyone at all.
Stop trying to engineer and force friendships. The kids play together at school, it is not your place or your right to force yourself into someone else's home or life.
She has ignored your demands for attention. Take the hint.
You are overbearing and controlling, as you said your mother was. And you are teaching your child to believe that your demands and wants are more important than other people's right to be left in peace and have their own choices.
This woman probably has excellent instincts and sees you for the strange, fixated, controlling, demanding, overbearing person you are who thinks she has the right to force friendships in other people's lives and homes.
I would like to believe you are not obsessively fixating on this to your kid and endlessly harping on about it to him as well, because otherwise he may well grow up to be just like you, and your mother.
It's not your place to tell other people who to hang out with. Your child will continue to be excluded because of you, unless you learn some self awareness, chill out and learn to accept rejection.
Nobody needs a reason not to hang out with you, or your child. But really, the reasons are obvious.