How do I talk to my brother about alcohol related dementia?

My brother is 54 years old and has been an alcoholic for at least 30 years he was recently diagnosed with alcohol related dementia just another condition to his numerous health issues respiratory failure, COPD, Congestive heart failure diabetes ect I gave been his caregiver for 3 weeks now and his dementia has spiraled downward very fast plus he still drinks I have mentioned the dementia to him but he gets real angry and aggressive he can't even walk anymore and he takes a few sips of beer and that's it He seems to have trouble swallowing falls a lot has both types of toileting accidents rarely showers and rarely eats I want to make sure he knows that alcohol is making it worse and that he may need more care than me and his wife can give he just hot home from 3 months in a nursing facility and 3 months in ICU I don't want him to go back already