All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
We recommend that you bring this question to the competent authority in handling the issues of the Muslims in your country, such as Islamic bodies, or orally consult a scholar.
What we can mention here in general is that the husband's saying to his wife: “I divorce you” is not explicit in divorce, so divorce does not occur unless the husband intends it. It may be that your drunken husband intended divorce if he was aware of what he says, but if he is unaware, then his divorce does not take place in any case according to the most preponderant opinion of the jurists.
The fact that your husband does not understand divorce, if it is meant that he is ignorant of the words and rulings of divorce – in the sense that he does not understand its meaning – then he is not required of anything, for lack of intention; however, if he knows what the word divorce means, but he is ignorant of the details of its rulings and words, his divorce takes place and this ignorance is not considered a sound excuse on his part.
We draw your attention to advise your husband in a good manner and remind him of the prohibition of drinking alcohol, which is the mother of all evils. Moreover, you should seek the help of some righteous people to admonish him, so that they may be a reason for his guidance.
Allah knows best.