Springs, my husband has been a "secret" alcoholic also. We are married for 17 years and together for 19, and I know that feeling of the bottom dropping out when you find out what is going on, and HAS been going on for years behind your back. You look back, w/your new knowledge, and suddenly all those things that just didn't seem quite right (but you couldn't put your finger on what was really wrong) suddenly make sense.
Oh, so he never wanted to go to the park and go swimming in the summer b/c it would interfere w/his drinking time, he always packed a really small lunch for work so he'd have an empty stomach, the quicker to get a buzz after work upstairs in his model-building room, he always had to keep cash on hand so he could buy bottles w/o leaving a paper trail....the list goes on and on. And the feeling is as if you are standing at the edge of a cliff while it slowly crumbles away under your very feet.
And yeah, it sucks. Hard. As you said, it's a long sad path to be on, and you find yourself going "wow, how the F did I end up HERE?"
I'm really new here myself, but I found that Alanon meetings did help keep me sane and went to several a week for a while. Now I've cut back a bit on traditional meetings but have some email groups plus SR. Also, I'm slowly trying to get involved in the outside world again, as I've gotten really isolated. I have made a volunteer commitment at 2 different places and am doing some hiking w/a group on occasion, and it helps SO MUCH to just get out and about and take your mind off your problems. While there is much that is F'd up, there is much that is beautiful and good, too. Just trying to see some of that every day helps a lot.
I found this bit of writing, entitled "Just for Today",
http://www.nhal-anon.org/Just4Today.html to be a great outline for how to drag myself out of the Great Swamp of Despair; hope it helps you too.