I will not bore you with my story, because you are living it right now. My ex wrecked his brain so much that he is no longer capable of realizing he needs help. And if he quit cold turkey, he could have seizures and die.
My advice to you is to be honest and if you have had a good relationship with your Mom, talk to her openly. Believe me, the day will come that something will happen that you will HAVE to tell your family and friends. Most of them probably already know. It will be a big relief. Find counseling for yourself if you can and eventually, you will find a way financially to take care of yourself. Right now it sounds as if the situation is overwhelming for you, and you can't make the right decisions for yourself. I understand that so well.
This may sound harsh, but the best thing that could happen is if he were to get arrested for something while he's under the influence, the courts may insist on rehab. And that responsibility will not be all yours.
You deserve better than to live with a pee soaked couch and I am praying for you! Because I totally understand how much time it takes to stop taking responsibility for someone we love, even if it's toxic to us.