I'm not the original poster, but wanted to respond unregistered. My brother has the same issues...more or less.
My brother has a history of alcohol and drug abuse (pot for the most part). My mom always helped him out and kept his habits afloat by paying the occasional house/car payment. He's done several month long stints in city/county jail for the last 20 years. His recent thing is to get high, drink, and run around naked and fight people. He started doing pot around 13-15 years old. Now, when he drinks, he reverts to that point in his life - changing how he talks and everything.
His annual income was around 20-30k year. He had 3 cars, a boat, and a condo...everything on loan, no savings. He likes to impress his 'friends'. Now that these things are gone, he has no friends.
Mom passed away 5-6 years ago. Blew through a significant inheritance in 2 years. Enough to buy a couple decent M20J's and keep them maintained for a few years. Has since sold his boat and 2 cars. Keeping the condo, but behind in payments.
In his last stint in jail, his condo was foreclosed. I packed up his entire condo and moved his crap into a storage unit - disgusting stuff. I paid for 3 months storagem the movers to haul the boxes, and his car (the only one paid off, its a pile).
While in jail, he asked to live with me. I said he could move in with me for a few months if he decided to sober up and seek professional help. He refused. One random night, he called from outside of jail asking to stay the night at my place just for the night, I didn't pick him up and said he's unwelcome at our house. He found a ride and slept in his car that night. There are no other relatives within 500 miles of here to help him. I've also been in touch with them and advised them not to contribute to his habits.
Eventually, he found a job and an apartment. After a month, started drinking again, lost his job a month later. Got kicked out of his apartment, back in his car. New job, new apartment....Rinse and repeat, now it cycles every 3 months or so. I have no clue where he lives, only that he lives in the same city somewhere.
He calls me occasionally asking why I won't help out his only brother. I said I would pay for treatment to get him sober, he refuses, says random stuff, and then hangs up. Rinse and repeat every 6 months. I see him about once a year for Christmas. I take him to dinner, but request that he shower before he sees me. He never visits or calls our sister who is mentally challenged. I have a care taker for her and she's doing great and enjoying life. I don't have the resources (mentally or monetarily) to take care of two siblings plus enjoy my life. I'm saving for my own wings right now.
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That's my history. I've had counseling for myself regarding my brother. My sister is cake compared to my brother and she is never an issue like this. The counselor has worked with many families that have to deal with family members in this circumstance. She has advised me on actions to take (not giving him a dime and not letting him stay with me) and why doing so only enables him to continue his drinking and drugs. She said that my brother needs to find his bottom, whatever that is, and that ultimately, even being homeless and jobless may not be his bottom. Only when he reaches his bottom and admits his problem, will he seek help. I've offered to my brother to visit a counselor for anything he wishes to talk about - his time in jail, mom & dad being gone, work, etc...he refuses (I didn't even mention to him to talk about his drinking or drugs).
My brother still refuses that he has a drinking or drug problem. He says he has to do it to keep calm and relax his mind. I don't know his habits now, but he was super lazy. Only getting off the computer games for the bathroom, fetching drinks and drugs. He never cooks, only fast food. When I used to see him more regularly when mom was around, he was always drunk and/or high and was very rare for me to see him otherwise. Mom and I joked that he probably can't function sober.
When I packed his condo up, there was piles and piles of rubbish everywhere - fast food wrappers, empty soda cans, etc. Mountains of dirty clothes. I used kitchen rubber gloves to pack everything...with a few fans in the window due to the stench.
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My advise. Kick your son out. He can sleep in his car just fine. NEVER give him money! I'll repeat: Never give money! If you want a roof over his head, pay his rent somewhere directly for a month or two. Only give a grocery store gift card if they don't sell alcohol. For gas, find a chain that doesn't sell alcohol (easy in some states, impossible in some states).
My mom wasn't able to do this, and it only enabled him for 25 years of drinking.
While I was moving my brothers stuff out and dealing with him in general, it put a strain on my relationship with my better half - to the point that we almost broke up. We're now engaged. Don't let your son ruin your other relationships - you'll need them to help you through this.
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I'm assuming you understand why I'm now posting this unregistered.
You can refer to me as "Andrew" if needed in any replies. I hope this helps the original poster...to at least seek professional help.