Hi Bill, I've considered this from several viewpoints:-
1) As a stupid 20-year-old I wrote off my car in the early hours of one morning against a brick wall in a Herfordshire village, and was so drunk I staggered to the phonebox and dialled 999 ro report it! This being 32 years ago, the coppers who swiftly attended and breathalysed me (it had just come into use) as being well over the limit kindly decided not to book me, however since then a single pint or glass of wine has almost always been my limit if driving/riding, unless sufficient time has elapsed at 1 x unit (not drink) being metabolised per hour.
2) Reaching a total of 12 speeding points lost me my licence a couple of years ago, but fortunately only for a 2 week period. As a 30,000 mile driver + 12,000 mile biker per annum, a much longer ban would have been a major problem but I would have stayed off the road whilst banned: the dumb bitch you've described might not, and then with any luck she'd probably be jailed!
3) I'm sorry to say that my own girlfriend will also drive short distances (alone) when she's "slightly" over the limit (and her driving is rather poor even when sober!), as do several of her friends both male & female. None of them have had a crash whilst doing so over many years, but maybe they've been lucky so far.
4) I'm not at all sure it's actually your personal responsibility to decide on a deliberate course of action/inaction: after all,where do you then draw the line? Who else are you responsible for? All your friends and their families? Complete strangers? Me? If, as seems to be the case, the "nanny state" has now decided that speed cameras are better for road safety than patrolling police, you can't compensate for such nonsense by worrying about everyone yourself instead.......
5) However, as you clearly do feel some responsibility, I suggest you talk to her husband when he's sober, as he definitely has some specific responsibility for the situation, especially with the kids being in her car when she's drunk. Warn him that you've heard a nameless person in the pub threaten to report her and leave it up to him after that - if he's still not bothered then it's simply not your problem (but you may wish to reconsider your friendship with such an irresponsible pillock).
6) Alternatively, you could confiscate her keys next time it happens, and tell her you've done her a favour this time.....
7) Personally, I reckon hand-held mobile phone users constitute just as much of a menace to themselves & others as drunk drivers do (and I bet she does that as well).
Regards,
Martin