Welcome,
I second, third and fourth what the other posters said.
Marriage is hard enough without going into it knowing your future husband is an alcoholic.
If he really wants this marriage, let him get sober and stay sober for a year, that includes him getting into a strong recovery program.
Alcoholism is a progressive disease left untreated he will get worse.
Where is your support system in all this, friends and family, are they aware of his drinking?
Read others posts, be smart think with your head not your heart. Your heart is not designed to do the thinking.