Wow JM, I know this guy you're talking about being with in 20 years, I'm married to him. Good news is he's in rehab and finally getting what I consider proper treatment and support for both his depression and alcoholism. But let me tell you a little bit of history...
My husband's depression started affecting him when he was in his early 20's and like you husband, depression runs in his family. Well he found that if he drank a few more beers that depressed feeling sort of went away, or was at least numbed. So he keeps on drinking them. But then he finds he needs more beer and more beer to keep the sad feelings away. And he also finds that if for some reason he goes a long while without the beer his hands start shaking and he really misses that "whatever" feeling he gets when he drinks the beer. Now he's depressed because he's so dependent on the beer but if he doesn't drink it he'll feel that depression. A viscious cycle has begun. Fasten your seat belts!
You said your husband was on zoloft. Well anti-depressants can't do their job properly if you're also indulging in alcohol. Says right on the bottle "Do not take with alcohol". Also, I'm of the belief that general practioners should not be prescribing anti-depressants. It should be done by a phsyciatrist and there should also be some sort of "talk therapy" involved.
I'm not trying to scare you but my husband's road to the proper treatment this time started off with a suicide attempt. I guess the 3rd time was the charm as this was his 3rd attempt.
My husband has been an alcoholic for around 25 years and for 24 of them he was a functioning one. The heartbreak of his daughter's rejection sent him down into the black hole of depression so he turned to stronger alcohol (vodka) to try to block it out. Turned him into a very, very depressed "skidrow" type of drunk
Ok, so what's my advice? See if you can get him to see someone who has experience in what's known as "dual diagnosis". If not then I'm sorry to say you and your husband may well be me and my husband in 20 years, if you last that long.
For you I suggest Alanon. Find out what will help to keep you sane BEFORE you're on the verge of going insane over it all.
I'll be praying for you and don't forget that we're here!