@YorkshireGirl2016 - I will very briefly explain my story for you, just so you can see a perspective from someone who has been in your shoes, however I must say @AttilaTheMeerkat points are very valid. However I feel I only agree with those points now I am on the other side of the line rather than being in the actual situation. I couldn't see very clearly at the time either.
My sister is / was an alcoholic and drug addict, coupled with I believe mental health issues. She has a young child. Basically the last 10 years have been hell on earth due to her addiction issues, which effectively got steadily worse possibly in part due to my enabling and rescuing behaviour that has been mentioned above. It has taken for me to say on the last visit to detox that I had 3 things which if she chose to continue to ignore, such as starting drinking again then I would walk away from her and that would be final. To date things are going ok, but I am also fully aware I need to stick to my decision firmly.
I was nearly broken by the time I got the internal courage to write that letter. I was caring for my nephew, skipping out of work, cancelling plans, lending her money and getting into debt. Writing to companies to try and organise her finances. I thought I was doing all this to help and all I was doing was causing myself untold grief and allowing her behaviour to continue.
I know its easy for you to drink to numb the pain, but I urge you to stop that if you can as addiction is far to easy to fall into especially if you are in a particularly vulnerable position.
Both of you will only change ultimately when you decide to change, but I do recommend you speak to Al-Anon, you cannot do this on your own.