I just read your thread from start to end and felt like I could have stopped on p 1 and predicted where it was going... And do you know why? Because I am you- you are me... I have been doing this dance for 8 yrs with my H. His behavior when we dated was intolerable but unlike you I never mentioned the elephant in the room. I got my ring, wedding, nice house, kids etc... and you know what else? I got the same guy you have but now he's my H and it's a LOT more complicated to end things. And I have 2 young kids who've been decimated by the chaos in this alcoholic home. As much as it hurts right now (and I'm divorcing my H and I am heartbroken too like you) I'm envious of your strength to break it off BEFORE you get married, join lives, finances etc... and you STILL have the same alcoholic you had when you were dating...
I'm sorry for your pain-- I really understand it and feel for you. Stay strong if you can-- he'll be full of sorry's and I want you back's again and I think you know how it will end if you take him back again... That said, it's taken me 8 yrs to get here so I'm not on any sort of soapbox...