If I had not married my A 18 years ago, I probably would have married someone else just like him. Several months in Al-anon have taught me that I have issues. I am working on them now.
X, if you are aware enough now to question the wisdom of marrying your A, you are miles ahead of where I was back then. Backing off of the engagement would give you time to know yourself better and see if you really want to go through with the wedding. It's much easier to undo an engagement than a marriage. You have choices, you just may not like all of them.
My marriage has given me the two greatest gifts of my life--my sons. But I am dealing with a lot of fallout from my alcoholic marriage, and my boys will always be the children of an alcoholic.
Take care.