Nowearefour...I think i may have fallen into the same puddle as you. Most of my friends are not too competitive, but one is, in the extreme.
I have just managed to potty train DS, and have kept very quiet about it, although at home am over the moon with him.
However, despite playing it quiet with friends, if one of them notices DS has had a change of trousers, such a fuss is made, loudly. I don't want DS to hear it, as I think it could set him back, as we play it low key when he has an accident.
I am open about how difficult it has been, and been honest about wet carpets, dribbles by the loo and the intensity of reminding DS about going for a wee, when asked by friends, and when DS is not directly around.
I say nothing to others about him...as it seems either competitive...or not good enough. As a result, I am erratic at attending coffee mornings, and social events in order to avoid the constant comparison. They all get to where they are going in their own individual way, and wouldn;t it be dull if they all did things at the exact same moment.
I am astounded that a mum of a child with SN was asked to leave a children's gym session. Surely these sessions are for everyone of every ability. I think she has the complete right to make an official complaint.