(i) godfather or relative to quietly read him the riot act
(ii) then present him with a contract for the rent, how much and when, what it covers in facilities. Outline his responsibilities and define what he is expected to do with a minimum of hours in the advent of unemployment. Get him to sign it, you too.
(iii) sort your mind out that he is an adult as I am sensing a little jealousy that he is devoting time to the gf, not keeping you fully in the loop and you may also be taking it out on her too. He is an adult and you have to accept that, he is no longer your baby boy. Last point, how do you know he will end up unemployed, that is a bit of an extreme position to take and if you are conveying that, you may be fuelling his "hostility" (the verbal abuse) and the lack of imparting information, even his want to have your birthday greetings.
I suspect that there are issues that you need to sort out, just as much as he does.