I had a coach like that in high school. Very nice guy, very encouraging, good sense of humor... until the ambient stress level crossed some invisible line and suddenly he was red-faced and screaming. He used to throw things to express his anger, and once spun around and hurled a clipboard without looking and missed those of us sitting on the bench by about one foot, max. It was, to say the least, somewhat unnerving.

My coach did make some effort to shape up after the clipboard incident (and also after he got red-carded out of a couple games), but he still got fired after the end of that season. It sounds like the husband in this letter isn't making even minimal attempts to change his ways despite his wife's expressed discomfort. That is not a good sign, and honestly, I hope he gets fired from his coaching gig (and possibly "fired" from his marriage as well).