OP, show him this from me:
I used to have an anger problem. I have behaved aggressively, hit people, and broken things before. I have hurt myself, frightened people I love, and caused damage in ways that I still regret.
That is a lot worse than what your situation is like, but it shows two things;
a) aggressive behaviour lies on a continuum, and even swearing to yourself in an angry voice can feel threatening to other people, because it shows potential to extend to violence and destructiveness; and
b) it is also something that can go in the reverse direction and get better.
OP's husband; Whether or not you feel someone else "inflames" your mood by responding with similar aggression, it's YOUR responsibility to learn how to deal with your own anger.
You are right, anger can be useful, and it is normal emotion which you cannot be blamed for, but aggression on the other hand is a behaviour that you have a choice over.
OP; responding the same isn't helpful for either of you, but you are right, it's not your job to calm him.
Ironically, I had a problem with aggression because I was afraid! I would absorb too much stress, fear, or aggression from others, and try to hold it all in, then it would get too much and burst out uncontrollably.
Neither of you are completely wrong or right here, but it's about taking a different angle. Why are you angry? How can you respond better to that emotion?
First, separate the emotion from the behaviour. Anger is the feeling, abd nothing else; your choice of words, vocal tone, actions etc., are chosen behaviours.
Then, appreciate, respect, and most of all express the angry feelings. They are normal and okay. However, note that when and how you express your feelings is where the issue is here.
For instance, OP, your husband may have been feeling frustrated with the situation, frightened for his child, helpless about how it happened or how to help, or any other feelings such as these. Just like I imagine you would.
I still remember instantly breaking out in a sweat whenever my babies cried (although it was worst with the first one and got better as I got more experience), panicking about whether they were somehow going to break into little pieces if I did the wrong thing. My heart would pound, and I'd get a headache quite often.
Maybe you both felt similarly. It definitely sounds like a stressful situation.
But what might have helped was for dad to say "I'm really worried!" or "Can you help me do 'x/y/z'?" etc., and to ask mum to hold baby while you get a splash of cold water on your face and take some breaths, and vice versa with mum. Be expressive in a healthy way, as soon as the feelings come up, then respond to them as a team.
It's no good expecting someone else to help harness your feelings, they're yours, and neither is it helpful to scold someone for doing exactly the same as yourself.
You two must have some good things in common, those are the things that can give balance. Focus on those.