I know it's hard, Pearl (hey, my mom's name was Pearl!), but his feeling sad and lost and desperate is exactly what he needs right now. I'm a sober alcoholic, too, and it wasn't until I was at the end of my rope that I was able to see what a mess my life really was and to commit to getting sober and staying that way.
Believe me, he is where he needs to be right now, and so are you. You can tell him you don't know if you will come back, that you have not decided and cannot decide until he has been sober for awhile, assuming that is the truth. If you come back too soon, it may short-circuit his internal need to face what he needs to face.
I know it's hard, but it's really for the best right now. You've already left, so let things stay the way they are for the moment.
Hugs,