To those who don't think it's a big deal..if it's causing him to sleep in the next day and not help take care of his kid, do anything around the house, or hold down a job, yes that is a serious problem. And if he's drinking AND driving, that is even worse. What do you think most people would say if SHE was the one neglecting her responsibiliti es? They'd say to divorce her ass asap, get a niam yau, send her home, etc.
My point is that it is a serious problem and she needs to approach it in a serious way. Biotching at him about it while he's drunk or having a hangover is not going to help. Talk to him about it when he's sober...let him know how his drinking has affected their lives and that he needs HELP. Let his family know that they need to stop drinking with him and tell them exactly how his drinking has affected the marriage, his child, etc.
Ultimately it is up to him. Some people have to hit rock bottom...if he doesn't think he has a problem, he won't take any steps to correct it. He may have to get alcohol poisoning a few times or hurt himself/someone else before he realizes there is a problem. And even then, if he's addicted..it is going to be tough