You can only control your own emotion/ behaviour and to an extent influence that of your children.
I don't think confronting anyone can help, however I do think you need to work on your self confidence.
You know your DS best. You know his needs best. You are able to educate others about those needs - its then in their court to listen/ absorb or ignore. I know that sometimes in families it is like hitting your head against a wall but other times messages may just filter through or they get fed up and just do things your way even if its just to shut you up.
My DSis 11 and Autistic. I've survived the bad parent years. My XH walked out when DSwas 3, younger DS1 so my parents knew it was down to my bad single parenting.
I have three lovely children now and I'm remarried. My eldest is (still) severely Autistic, middle one NT and youngest on the spectrum but we're still working out how much of an effect her particular traits are going to have on her.
I find that sometimes i need to just be assertive and take control of situations because thats what DS needs. To an extent its putting DS's needs above that of others, but sometimes its important to just fight your own battle.
For example a while ago we went to see the giants in Liverpool. They were to be right by the trainstation only a few stops along from where we live. We had ear defenders etc and thought we'll go, look at the giants, get home again. It was something my sons Grandpa really wanted to do for his birthday and various family members were going. We got on the train which was heaving. DS has dyspraxia and is very uncoordinated. Standing on the train whilst moving isn't an option for him. I went over to the children in the accessible seats and asked if they could shift over a bit so DS could sit on the end because he's unable to stand. They moved and sat on their parents laps. It made such a difference to us because he couldn't of stood up, would have been very overwhelmed by attempting it, could have got injured/ hurt others etc.
It did take effort on my part to have to explain/ outline his needs with the risk of getting a mouthful. But it ment our needs were better met.
It is tough. Do you have a local carers group,you could join? I go to one every few months. Its really good for having a good laugh about the rediculousness of some situations with others who know exactly what you mean. Oh and I've met loads of other bad parents too. Just about everyone i've met at carers has come across the bad parenting acusation and been bruised by it.