I am sorry to hear that. Most likely, he knows that alcohol is disallowed in Islam, but doesn't care. (There are many things Muslims debate over; alcohol is rarely one of them.) He may also have some dependency on alcohol. You can advise him, but in the end he will make his own decision.

What you should do depends on yourself and the situation. Sometimes, drinking itself is the problem (for instance, if someone becomes violent or overspends because of it), and sometimes it is symptomatic of other problems (here, a difference about religion, and/or other problems in the marriage - often, people are willing to overlook a great deal if a marriage is going well, even if they disapprove of it). 

I think you should consider your situation holistically - how is the marriage overall, what are your options financially and practically, are there other concerns,  would you lose contact with your children if you left him, and how much psychological stress is it causing you  - and talk to someone you know in person who can give you good advice based on your situation overall. Also, many religiously minded parents want their children to be raised religiously, and if your husband would have custody and is not religious, it might not be what you want (I am sure you have already taken that into consideration). 

While it's advised in hadith not to marry someone who drinks, that is a decision to make before marriage; now you are in the marriage already and have children, so it's a reality you have to navigate and make the best choice about. In the end, it's something you need to sort out for yourself, because advice for one person will differ from advice for another person.

With duas!