Yet another screaming argument

Or rather, yet another screaming monologue with me standing there being yelled at and cussed out in front of our kids. 

I have a special needs adult son who asked Dad this morning if he could go buy a video game he's been saving up before school on Friday. He said no, they would go after school, and Henry got upset. Rather than encouraging his special needs son to slow down and think of alternatives, DH just got loud and started arguing and yelling. I'm getting ready to go to work, I'm not hearing the discussion until they both boil into my room yelling at each other. I immediately told them to stop arguing, stop yelling, so I could ascertain the issue. I got my son calmed down (btw he's like 4 years old mentally, you're not going to win an argument with him, you have to try other tactics, as I've told my DH like a million times). 

As I'm going out the door I mention that yelling never works, and that instantly triggered him into a full blown screaming fit at me for 10 minutes, cussing me out, telling me I treat him like a child (if the shoe fits), that there is no other option to deal with things other than yelling and arguing, etc. I just stood there and let him yell at me for 10 or so minutes, my son was screaming in the background, and my daughter came out of her room crying. 

So yeah this is not the first time this has happened, more like the millionth time. I let him treat me like this. I enable his behavior by allowing him to continue to treat me like this. I've shown my kids that it's okay for people to treat them like this. 

I want him gone. ADHD is a monster. I see nothing positive about it. I've read all Melissa's books, and I've tried all the tactics, and nothing ever works. 

I would love advice on how to move forward - how do I tell him I want him out. I don't want to be screamed at but he's incapable of discussing anything without doing that - which is why I don't talk to him about anything.