Just needing to get this off my chest somewhere safe

Had a day out with my son today, lovely day, place we've been to many times and always really enjoy ourselves. Shortly before we were going to leave a man pushed his son in front of mine in a queue for a ride and my son missed his turn. I pointed out to the man what he'd just done and that my son had now missed his go and he shrugged his shoulders and turned away. This made me very angry.
I spoke to the man about this later (when he was alone) and said I thought he was setting a dreadful example to his son by pushing him into behaviour like that. The man's wife came over and had a real go at me, saying that I was aggressive, verbally attacking them, following them round, ruining their day out and that I'd humiliated all the people around me when I'd spoken to her husband. When I pointed out that the least he should have done was apologise she ignored that and just repeated everything she'd said before.
It was horrible, humiliating, embarrassing and a very unpleasant way to end the day. She threatened to get an official to sort me out and told me to stop following them and harassing them. Her husband had disappeared without saying a word before I'd even finished my first sentence.
I felt physically sick, was shaking and felt like crying.
What I thought about on the way home was that I could have just said nothing at all, or I could have walked away when she started her tirade. But I feel that what they did was wrong and I think I should have said something.
I was polite, level toned and non-confrontational, although I did raise my voice at her nearer the end when she said she felt sorry for my children. That made me angry.
I feel I should stick up for my son; to me it was important to show him that his place in that queue was important and that their behaviour and lack of apology was unacceptable. I would have preferred him not to have seen the row afterwards but I feel I handled it reasonably well, without swearing or making threats (although I really just wanted to give her a slap). It was just a shame the day finished like that(although to be honest I don't think he actually noticed what was going on as his autism makes him rather insular).
Anyway, just wanted to get it down on paper (screen!). Thank you
