*sigh* Addicts sure are good at what they do aren't they? I'm sorry for you. I'm really sorry.
The good news is, you had a plan back then and you can go back to the plan. If it helps you feel less taken advantage of, my AXH had his sponsor, his AA groups (yes, groups, as in 2 homegroups), convinced he had been clean and sober for years. In the meantime, he had replaced his addiction with pills. Big time addiction. He fooled everyone for years. The last few months I knew, but was working on getting out. Just made sure he was never alone or driving the kids. Once I kicked him out, he came clean with everyone. He still has AA people who won't speak to him, because of his lies all those years. So yes, your AW is a good liar. Addicts are.
This article helped me a lot: (um, it won't let me post a link: i'm too new! so google 8 easy ways to spot an emotional manipulator)
(ignore the rude language, but really read this description). This is probably who you are dealing with. At least in part. If you can relate to the description, remember it during the divorce part. Compartmentalize and use the info. I did and it paid off. Now, put on your big Papa Bear shoes and take care of the boy. He's going to need a nice strong parent. Tag, you're it.
It gets better. Today is one of your worst days. It gets better.