Misseh

Well were do I start,
I guess this really doesn't concern me but as an outsider I can see it all too plainly.
Basically my boyfriends brother is an alcoholic, he won't admit it, yet he is reliant on alcohol. If he doesn't have a drink he's grumpy and if he has one, he's a psycho who's aggressive, when he wakes up with a hangover again back to grumpy.
Everyone is on tender hooks, walking on egg shells. Just the slgihtest thing you say to him you get an over reaction. Regardless if he's drunk or not. For instance tonight.
He's not been home for 2/3 days, the family have been absolutely fine. His mother a little stressed as she worries for him when he's not home. He's used her credit card and basically gone AWOL with it. He comes home, clearly has kicked stuff en route to the kitchen where he stuffs his face. Says to his brother "what's the best way to kill yourself?" Brother replies along the lines "well you don't want to be doing that" I say "yea you never know when things may change, I've been there and trust me I wouldn't want to ever do that now" his retort "shut the bleep up *insert my name here* just shut the bleep up before I punch you through that bleeping wall" of which I have to just shrug and go "yea yea watever".
It's not the first time and shan't be the last. He works really hard and now and again gets too drunk the night before and misses a mornings work, he's known to be social with his work mates. But as soon as he walks through the door Mr Hyde comes out to play. The family gets shouted at, he starts threatening everyone, kicking punching walls objects, starts trying to start fights, threatens to kill himself, goes into psychosis of some description, talking to himself, bringing up jealousy toward his brother.
He doesn't realise he has a problem and the family is suffering. His brother and I usually get the brunt of verbal aggression and I think his family are too soft with him. If it was me doing this to my family, I'd be kicked so far up the bum, I'd be coughing shoes, I'd be kicked out and left to my own devices.
His parents just moan and say the same thing over and over again, clearly this is just a cycle and will never end unless it escalates too far. I really do think he's a danger to himself and society. He has often come home after fights and thinks it's ok.
How can his family stick up to him and show him this is not ok any more? They're 60 and 70 years old and the stress is eating his mother up inside. She will regularly shout out my boyfriend about nothing, or blame him for his brothers attitude or behaviour, when my boyfriend is NOTHING absolutely NOTHING like his rude arrogant brother. If assault was legal in the UK I'd be slapping him around the house with the way he treats everyone. I'm sick of it, it puts everyone in a bad mood and everyone takes it out on each other instead of him. Any idea's how to suggest help for him or to talk and advise his parents as to what to do? I'm at my wits end. Any help would be very much appreciated!!