I shamed one of the other mums in my group. Did I go too far?

(This could end up being a long post so my apologies for that)Since my 8 year old son Zach was born, I became part of a sort of informal ''parents group'' who had kids born around the same time. A lot of them now go to the same school so we meet up regularly.Not all of us are close to each other. I barely interact with Elaine outside of the group, not for any particular reason we just never grew close.Elaine's daughter Ellie is the informal ''celebrity'' of the group. She was an early developer. Started speaking and walking much earlier than any of the others and has always been very advanced for her age. She picked up reading, writing, spelling and maths very quickly, and at this point she has completed tasks intended for 13/14 year olds. This is fantastic and it must be lovely to have a child so talented, but unfortunately Ellie is also a huge bully to some of the other kids.Zach doesn't like her. When the group used to organise play dates a few years back, Ellie used to constantly steal and snatch things from him, and say mean things. Zach is a sensitive child so this upset him a lot. I have taught him you do not ever hit or scare a girl (or anyone for that matter, but especially girls) and have tried to explain how to stand up to bullies ''nicely''. But even if he did this Ellie used to run to Elaine in tears, saying Zach wasn't being nice to her. Bear in mind that we were all watching this and it was clear as day that Ellie was picking on Zach. Elaine insisted that they were just playing around and that it was Zach's fault for spoiling the fun. If I pushed the matter further Elaine had the nerve to say that I was making out that Ellie was the problem because I was ''jealous'' that Ellie was gifted and Zach was average. From then on I kept my distance from Elaine and tried to limit the time Zach spent with Ellie.Some of the other mums/dads in the group admitted they also had concerns about Ellie's behaviour. She had a little friendship group and the parents of kids who weren't part of it said their children were teased and made to feel excluded/unwelcome. Elaine never punished or tried to control Ellie's bullying behaviour, and I couldn't help but notice Ellie bursting into tears at the slightest hint that she would get into any trouble, and when that happens Elaine tries to paint Ellie as the victim. She has also accused other parents and their kids of being jealous of Ellie's talent if they had a word with her about the bullying.Yesterday it was Zach's friend Sam's birthday party. Sam is a lovely boy who's mum thought it was only fair to invite everyone in the class even if he was only close to some of them. Ellie and her friends were invited too.Everything was going well until towards the end, when a girl called Rebecca (a nice girl who is friends with Zach) ended up crying to her dad because Ellie and her friends had been teasing her all day. This resulted Ellie crying, Elaine insisting that it couldn't be her daughter's fault, and then attempted to accuse both Rebecca and her dad of picking on Ellie out of jealousy. I have been very stressed due to work and other things, and for some reason this made me snap. I started shouting at Elaine that being smart is not a pass to be a bully, and that Ellie is a spoiled and rude child who needs to be taught boundaries and how not to hide behind her tears. I also said that she was much of a bully as her daughter.Elaine and Ellie left early, but I got a text from Allison, one of the other mums, demanding to know what I thought I was doing humiliating Elaine in public like that. To be fair I did manage to keep my rant out of the earshot of the kids (except Rebecca and Ellie) but even so I understand the point about shaming her in public, but at the same time I think those things needed to be said. It may even allow Elaine to do some hard thinking about her parenting choices.Did I go about this the right way? via /r/Parenting https://ift.tt/2JdqNWo