That's terrific, Alison. I would try my best to keep it up even if it doesn't work out quite so perfectly the next time. These are well-worn behavioral grooves, especially for him. It is probably much, much easier to get angry with you than it is to examine what is going on inside and figure out what is really going on. Picking a fight and blaming it on you has served him for a long time and it is very possible that this may be two steps forward, one step back for a bit. But, I also think the more you can work on not taking it personally when it does happen, it both helps him by taking the wind out of his sails and helps you to not get knocked off balance by his emotional turmoil.
And it is awful that his colleague is sick. Is it Covid? We brought in grief counselors to my work after the death of my colleague a couple of months ago, and one said something that really stuck with me (I don't know if I mentioned it here or not, but I will because I think it is relevant to how your husband may be feeling). That usually if someone passes or is very ill, it is something that happened to them. You can imagine also getting cancer or in a car accident, or that happening to a family member, but it is still not a shared experience. In this pandemic, Covid is happening to all of us. We are not only sad or concerned about our friends who are impacted most severely, but the anxiety for ourselves, our children, our parents, etc. is very real and gets more intense the closer it gets. So there is a lot to process with the pandemic and friends getting ill, beyond the usual. (And even if it isn't Covid, someone being sick right now with anything could probably trigger a similar set of feelings.)
Me (46) H (42) M:14 T:18, D9 & D11 4/19 - 12/19: series of escalating BDs 9/20 - present: R and piecing