Hi Nelliesmum, I know it is hard to understand such an awful illness such as alcoholism.
I am a recovering alcoholic myself and have now been sober 2 1/2 years...
Alcoholism is a very selfish and devious illness, as to an alcoholic, booze is cunning, baffling and powerful.
Your Dad will be drinking secretly because he is trying to hide how much he is drinking and because he feels ashamed of the quantity and probably times of the day he drinks.
The compulsion to drink is very strong and more often than not an alcoholic will physically need to drink and not have the urge to get drunk. This is just a consequence of drinking.. Its like self medicating and overdosing.
Its a vicious cycle... He will need to drink to keep a clear head, feel fairly normal, keep the "washing machine thoughts" at bay and not feel jittery and sick.
It takes alot to break the compulsion to drink, especially if he is completely physically addicted. Stopping could and probably would cause the DT's (google it). They are terrible and feel like you are going to die.....
Unfortunately the only person that can put an end to this is your father. I found the AA worked VERY well for me, and it was great to talk to other recovering alcoholics.
Many Alcoholics feel that it is only themselves that feel the way they do, talking to others does help.... Alot will tell the exact same story and describe the same feelings.
Hope this helps, just ask away if you need any more insight...
Itworksifyouworkit.