Again, stay in a matter-of-fact place. "We said we wouldn't yell. What would work when we start raising our voices? Would you be willing to put your hand up in front of your face when you are feeling like yelling? I will too. That would help each of us know we are aware things could escalate, and we would hopefully continue with a calm, toned down reply.
Know that if you don't talk about what is bothering you, the situation is very likely to remain the same. Get clear on what you want and need to be happy. Take into account the benefits of what you have now and the benefits that are missing. Sit with those facts until you decide to stay put or to move on. Feel free to call me for a complimentary 30-minute session exploring what is and isn't working in any situation you are currently in. I'm at 206-938-8385. We'll find a time that works for us both.