dmmarch I also agree you need to listen to your gut--that is what told you to call off the wedding. I think this was wise. There is no reason to rush into a marriage ever.
I was where you were right now a number of years ago-and we had put money down on a house on top of it. I lived with an alcoholic that has been in denial his entire life and although the best he ever did was outpatient treatment-he did not want to recover. He wanted to shut me up. I finally divorced him when I could not take it anymore and it started to impact our kids. I am not sure why I waited as long as I did. Well, actually I do. I was a raging codependent. Once I started working on myself I could not stay because the blinders were off and I started to take care of me and the kids and left him to deal with his own stuff.
He did (does) the same thing. The tossing of guilt to make it seem like it is my fault he drinks, his life is crappy, he cannot get a job, fill in the blank. He has admitted to me he is an alcoholic at points during our marriage and told me he is ashamed of himself. He may have been, but that did not stop him from drinking or drugging. It was not enough to make him stop.
You did not make him an alcoholic and there is nothing you can do to stop him from being an alcoholic. If you can get your hands on Codependent No More by Melody Beattie and/or go to an AlAnon meeting it may help you answer some of the questions you have.
I'm sorry you are going through this. It is really hard. Hugs to you. You will find many caring and wise people here. SR has helped me start to regain the person I lost-me.