My mother is an opioid addict (sleeping pills and painkillers), to the point that I'm considering cutting contact completely, because after 5 years of trying to get through to her and get her help she still won't even admit she has a problem and it's just getting worse and worse. Everytime I talk to her it leads to two days of anger, frustration and a sense of hopelessness. I tried it out for 3 months, not talking to her at all cause they had cut off her phone (she had spent all bill money on spending sprees while high) and she couldn't call me, it was the best 3 months I've had in a while, but then she started borrowing the neighboors phone to call once in a while.
Addiction is a horrible thing to have, and one of the toughest things a person can go through. It's even harder to admit you're an addict in the first place. I used to be addicted to alcohol, and refused to listen to reason. I could see the empy bottles in my bin and the receipts in my wallet, but I still carried on denying it until I was blue in the face. I only started to accept the truth when I was involved in a traffic incident. I had my family and friends walk away from me, and it took a lot to get them back in my life, but I will never forget how low I felt during that interval between the incident and my friends coming back into my life.
My advice to you would be to not give up on your mother. I completely understand it's a different kind of addiction, but it's an addiction all the same. Addiction is a mental illness, and it can destroy lives. But it can also bring people together, as was the result in my example above. Your mother will, eventually, realise that she has an addiction. It is essential that you are there for her when that moment comes because, trust me, she will feel alone. She will be in pain emotionally and physically, and she will need her family and friends there for support. And don't forget that when she does admit she's an addict, there are a ton of support groups she can turn to to help her through her ordeal. Until then, just hang in there as best you can. I'm sending love your way.