Thanks for your question.
I can certainly understand your concerns about your husband, however it does seem like he is taking this problem seriously which is a great sign. If these are behavior patterns that have been in his life since childhood, it's going to take some time to completely free himself from those things. Because of that, it's not uncommon for someone to continue to struggle periodically, which may make it appear that he is temporarily regressing, or that he is not using the tools that he has been given.
In most cases, as long as someone like your husband remains dedicated to making improvements and working with his therapist, these incidents will continue to get further and further apart. Part of the problem is that your husband is likely responding instinctually during those problematic times, which is why he is able to see it in retrospect, but not in the moment. You are right to not back down, and it is good that he is able to take ownership afterward.
It takes a lot of time an energy to break some of those negative responses that he has always resorted to. Even with the proper tools, getting past this often can sound a lot easier than it is. It does seems like your husband is dedicated to the process, and is trying to take responsibility for it. It also seems like you are responding to this properly. If you've noticed the same pattern happening every two months, it may help to point that out to him so that when it happens again, he is able to identify that and handle it differently the next time. Otherwise as long as he keeps working on this, there does seem reason to be encouraged that you will continue to see improvements.
I definitely wish you the best with all of this, and if there's anything else I can do to help please let me know.