Thanks, Blue. That's all sound advice.
Update: last night he came home late from work, looking a little tipsy. We had dinner quickly with the kids and then I had a meditation class (awesome and highly recommended). When I came home, he said he was taking the dog for a walk, and he tried to pick a fight with me when I said it looked like the dog was limping. He thought I had said the dog was sleeping, which he interpreted as me criticizing his decision to take him for a walk. (!)
Then I knew he was either already drunk, spoiling for a fight, or he was itching to go out and get booze, and he took my dog comment as an indirect attempt to impede his plan. (It was none of the above--just a comment on the dog's leg.)
He came back an hour later after I'd put the kids to bed and gone to bed myself.
At 1 am I was awakened by the TV blasting. I went downstairs and asked him to turn it down and he said 'yeah yeah,' as if I was being unreasonable.
Half an hour later the TV was blasting again; I came downstairs again and he was passed out on the couch.
At least he didn't come upstairs and harass me or the kids, but I'm very discouraged. We have a family vacation planned in two weeks, and I want to ask him to please not come. He knows he needs more help; we had this discussion with his doctor 6 weeks ago when he (finally) let me come to an appointment. That's what spurred his meeting attendance and almost a month of mostly sobriety.
He also, however, appears to want to continue drinking. I don't want to continue living with a drunk.