My advice is...If you are having doubts about marrying him, then DON'T. That would be my advice to anyone, but especially to someone contemplating marrying an addict. Please don't tie yourself legally to an addict until they prove they are no longer active. After a year or two of consistent sobriety and working a strong program, you can always reconsider getting married.
Your family culture isn't who will be living with an addict. You are. Your family will get over it, but you must do what is best for YOU.
Welcome to SR. You'll find a lot of support here.