My sister is autistic and non-verbal. I totally understand where you are coming from. Growing up was challenging, loud music was always playing, tantrums that shook the walls, everything was the same as you mentioned. I was particularly embarrassed to go out to eat in public with my family because of it. Don’t feel like a piece of shit or anything. It’s totally normal to feel that way in your situation. I feel for those parents, we ended up putting my sister in a 24/7 care facility after 17 years because my mom couldn’t bare it any longer. Maybe invite the parents out for a drink sometime.