London-flyer, sorry for yet another comment from a relative layman, but it seems that you may be in a hole yourself (with this chap's threats).
I don't think you have any option but to report him to his senior management/HR department, copying the CAA. You have your own livelihood to protect, you have to move before he can exert any influence. In the meantime, people's lives are at risk, as well as the credibility of the airline profession.
You cannot rely on his wife (who understandably will be protective but may not necessarily be skilled at dealing with the situation).
It's not nice, and I don't envy you, but I've had to deal with alcoholism in the workplace - equally ugly but thank God, innocent's lives were not directly at risk in that situation. He needs professional help.