When my guy is like that nothing I say or do is going to be right. It's pointless for me to engage because it just adds fuel to the fire. So the only thing I can do is take myself out of the situation until he's able to regulate himself. I give space.
When I can see the "freak out " coming?? I know my little questions ("what do you want for dinner? How was your day? Do you need any laundry done?" etc... ) are TOO much for him so... I give space. It's done out of love.
It took a long time and a lot of needles arguments before I figured that out. A lot of times he was looking for a fight and I wasn't going to do it anymore. I told him if he xyz, I'd leave the room, restaurant, party. And I did. Every. Time.
He finally figured out if he wanted to engage with me he better calm his ass down and show some respect or I would walk away.
Nowadays, he usually removes himself.
To answer your question there's nothing I can do to help regulate him. He has to do that on his own. I can only give him the space to do it.
Good luck!