Husband blew up during worksheet discussion

I don't even know what just hit me. My husband and I sat down to listen to Session 3 of the couples seminar, and we were discussing our worksheets beforehand. During our anger worksheets discussion, I said that I answered one of the questions according to my resentment because I don't really have anger. He asked me what I was resentful for. Normally I would not answer because in the last 6-8 weeks, he has been very irritable, and little things set him off. But I figured--hey, we're having a nice honest talk, so I will try to explain. Well, he immediately rejected my first answer because, "I do way more than the guys in that book." He could not understand why I would feel resentful at having to take on most of the child care, manage the household, and make sure things get done, because he does his fair share of the chores (we both work full time). When I tried to explain nicely that it is not about comparing him to anyone in the book but about addressing our issues, he exploded. He told me we don't have that problem anymore because he is done. He mentioned divorce (hopefully it is just his anger) and stormed off. (That has never happened before.) I was stunned. He wasn't even making sense, and I feel like a truck just hit me. He asked me why I felt how I did and then did not "agree with" my answer, which of course is unfair, to say the least.

I know this is just another of his anger outbursts, so I don't take it personally, and assuming (which right now may be a big assumption) he realizes that his reaction was irrational, my question is, how do we effectively make progress going forward? Should we not discuss anything heavy until the completion of the course? I feel very afraid to be honest with him because these reactions are quite frequent recently (it was not like this before his diagnosis, so I know some of it is his own dealing with this). But every time he acts like this, I feel more reluctant to share my feelings. 

I read in another post in this forum that the first year after the diagnosis is the worst, but how do we even make it to a year if he has this much anger and doesn't fully buy into the course?