He's what they call a functional alcoholic, but an alcoholic nevertheless... it appears he is also becoming a closeted one too.
I'm sorry you are going through this Deucalion. ::hugs:: The only comfort I can offer you is that is if something like this is for you where you would go.. to advise you to seek out your local chapter Al-Anon. I've enclosed a link for you for locations in the UK
http://www.al-anon.org/meetings/unitedkingdom.html
They help spouses, children, friends/ lovers, family of those who have a drinking problem... I'm not sure if you are familiar with it but other people are there with the same issues you are facing, some who have moved passed it and are just sharing their experience, others who are still in it.. You can talk about it, get feedback if you want, but mainly hear how others dealt with it or are dealing with it; what worked for them which may give you some ideas of your own to pick and choose from.
You'll get through this ::big hugs::