YTA: What your son claimed to have is real. If you haven't figured that out yet after everyone in the thread telling you, then there's no hope.

BUT I want to address how you treated the rest of your family. You're framing your wife as being unreasonable here. You brushed her off, and then came to reddit and made a post where you're acting as if she's a bad guy for taking the side of her child. A child that you, in case you haven't picked up on it yet, emotionally abused by pitting his autistic little brother against him.

You weaponized your youngest. You put him in a situation where you knew that what he was doing was upsetting your eldest, disability or not. Do you think he likes being used as a threat? Or do you think he's too dumb to know that he's being used to upset his brother?

All of this... Because your son has two sensory triggers that you could easily do your part to manage. Chew with your mouth closed, remind your youngest to chew with his mouth closed, and play guitar quieter. That's it. That is all that was required of you. And yet you behaved like a child.

If they all leave you, wife and youngest included, conduct like this is the reason.