Understand your pain, I too wouldn’t write something in a mail that I wouldn’t speak openly with the person involved.
I too suffered this about 15 years ago, during a corporate merger one MD was being a complete cock on a number of points, none that mattered. We racked up a Legal bill the GDP of a small middle African country and I let rip in an email outlying the pathetic attempts at derailment…. and cc’d the MD in in error….. To say I got torched from on high and actually verbally attacked at the next ExCo was an understatement to say the least. Had the rest of the members not supported me Ida been out on my Arse sharpish, truth is they did and a showdown at the table ended with him walking out with a small redundancy package instead of being shifted sideways.
I didn’t come out of that too well either, one of the Partners called me a pleb and poked me hard in the shoulder whilst staring me down..
Years later he was brought to task in a rather widely know banking institution collapse..
Edit,, I wasn’t an MD nor Partner before you all think WTF, I was there representing a large part of the Business (me and 7 others each looking after a Cluster )