Huge thanks to all who took the time to respond. I really appreciate your thoughts and willingness to share your own experiences. It makes me feel much less alone (and even somewhat hopeful

).
My husband and I have talked several times since I first posted this thread. I explained to him that I think he's not only suffering from alcohol dependence but also depression as well, and that the two are undoubtedly feeding into and perpetuating each other. At first he didn't agree with my assessment. Then last night, he admitted that he had been thinking about it and now believes I'm right.
Unfortunately he holds the stereotypical male view that depression=weakness (and that admitting to depression is an even bigger weakness). Of course I explained that this isn't the case and that admission is actually a sign of strength. He doesn't buy it. I don't know if that will change, but at least he was willing to open his mind enough to admit the possibility.
He also explained that he's been imagining what it would be like to end his life. He insisted that at no point did he ever have any actual intent to commit suicide--he was merely imagining what he would do in the hypothetical scenario. He knows we would all be devastated and assured me that he doesn't really want to die. He just thinks a lot about what it would be like to decide not to be alive any more.
It still seems like there's very little distinction. Is it normal for depressed people to fantasize, if you will, about committing suicide but not have actual suicidal wishes?
I really should be able to answer my own question. I've been there.
I remember how close to the edge I got a couple times and worry if my husband having similar thought processes now means he's worse off emotionally than he claims.
Anyway. The bad news is that he's still totally resistant to the idea of treatment or medication. I believe that private one-on-one sessions with a cognitive behavioral therapist who specializes in addiction and depression (in other words, just like the one I'm seeing now) would be beneficial to him, as would a low-grade antidepressant (again, like the ones I'm on). He's glad that these things have been beneficial for me but still insists that he doesn't want to go that route. He's an adult and I can't force him. Like someone wisely said upthread, what I can do is be supportive of positive decisions and always be there for him to confide in.
The good news is that we're in the process of moving to a beautiful house in a gorgeous town close to his family. His family are all awesome people. He has a really positive relationship with them and they've been very helpful and supportive so far. His older brother is three years sober. So that means he will have an excellent support system of people he trusts and loves who understand what he's going through. Perhaps if the problems persist once we're settled in, I'll be better equipped to persuade him to try counseling.
So all in all, I'm still worried but cautiously optimistic. I think it says a lot that he was willing to confide these things to me AND that he finally admitted the possibility of depression. We'll see how things go with the move. At least it gives him plenty to focus on in the meantime.
Thanks again for your kind words and help.