So sorry to read your difficult story, you have all done well to establish your independent lives. You don't mention having sought any support for yourself and your sister(s) -you really should check out Al Anon, I'm sure there will be one near you.
The support you receive makes you realise that you are not alone, but more importantly that you can't prevent this disease-it points out that in curious ways, by our very caring we are enabling the drinker to continue.
Sending you all good wishes across the North Sea!