Wow. Hugs, mama. I can't even imagine how terrifying that must have been. And hurtful and angering and sad and everything.
Please be gentle with yourself and take the time you need to process what happened.
I don't know if this will be of any help to you but one thing jumped out from your post when I was reading it (bolding mine).
Originally Posted by APMom98
Ds got angry because the girls weren't being quiet. He was trying to say something, and while he had my full attention, they were still talking and he was angry. So he started yelling. We are on the way to hockey at that point. I asked him to please not shout in the car and that it wasn't necessary for them to stop talking, I could hear him just fine. He wasn't happy with that, and kept yelling louder and louder at them. I told him that this wasn't a respectful way to treat them and to please stop or we would go home instead of going to hockey. At which point, he screamed "SHUT UP!"
This stands out for me because I really really suffer with being highly sensitive and with that, when I get overwhelmed, I get to the point where I can't take any over-talking or background talking, especially in a small space such as a vehicle, often cause the radio will be on as well. When I get over stimulated things start sounding freight-train-in-my-living-room loud and everything starts hurting my ears and I start feeling very angry as I try to find a way for things to quiet down. I can't continue my conversation because I can no longer think - everything around me - all the sounds, smells, textures - interupt and overwhelm me. So while my BF or friends wouyld tell me it's OK they can hear me it's not OK for me. It's taken me a long time to realize that's what's going on and that's what is triggering the anger. Often, especially when I was younger, I found myself screaming "shut up" in an attempt to make it all stop. Figuring out what was going on has helped tremendously in finding ways to cope and in eliminating the anger. But even now, as we head into the 2nd week of holidays and lots of people home and around and lots of space sharing I am finding myself needing to retreat to my room for some quiet and alone time. My family is starting to over stimualte me, despite my love for them. Just tonight I went out alone for a bit.
Anyways, I just thought I'd put this out there. I don't know if it applies at all or if you've seen some sensory stuff with him before.
Again, take care of yourself as you come down from the crisis and look into possible reasons for his behaviour.