rose, u show a lot of keen insight on your firends drinking problem. if you wanted to reach out to him in a helpful way, why not ask him about his drinking problem? maybe he would open up to you. if he does you could recommend he seek help.
another thing is you could offer him the reasons you are concerned, pointing out driving while intoxicated, isolation-yes, this is a symptom of a drinking problem, and that he seems to have changed since he started drinking a lot more, typical also.
there are two ways this could end up....he denies there's a problem, very typical, or he listens and tells u he wants help. there are 12 step recovery programs he could attend or he could talk with his doctor about his drinking and get a referral from him.
you are correct that this is disrupting your life. many of us that had drinking problems in the past took people as "hostages" as we call it. in other words he's not working on his problem but using you as a diversion and interfering with your life. you sound like a kind friend. i urge you to think about what i wrote and hope this provides you with some helpful suggestions. i wish you well and hope this turns out for the better...that your friend gets the help he needs.
if you do decide to try what i suggested then you can tell your friend that as much as you care, you'd prefer he not come over until he gets the help he needs. (i know this sounds harsh but it is not your responsibility to "babysit" him while he's messed up.) you can offer to go with him to a 12 step rec. meeting if you are willing to take the time to support his efforts. that's entirely up to you.
just noticed your reply post. what i've suggested still applies. the only difference is that he knows there's help out there and also that it is possible he already has liver damage. all the more reason to intervene and set your boundaries with him, imho.