Posted about this many times on MN and always had very good advice.
My mum is a functioning alcoholic. Always used drink to cope with stress but since my dad died 4 years ago it's gotten steadily worse. Daily drinking, often in the mornings when she's not working. Isn't abusive as such when drunk but can be argumentative, forgetful and just generally talks rubbish. She slurs and behaves bizarrely it's just very unpleasant and embarrassing to be around.
I've spoken to her about it many times, things don't change. I understand she is grieving but ultimately alcohol has always been an issue for her and I think since we lost dad she has used it as an excuse to simply drink more and more. I do try to involve her in our life - she comes on holidays and days out with us. But often she will prefer to stay home alone drinking.
My question now is how to respond when I know she's been drinking. For example I can tell within seconds of her answering the phone if she's had a drink. Rather than address it in a mature way I tend to just get grumpy and end the call as quick as possible. Then I end up feeling guilty about treating her badly. Today I spoke to her at 10am and knew she'd been drinking. I was abrupt and ended the call. My dd said 'you really don't like grandma do you?' And it broke my heart a bit. So I thought I need to find a better way to communicate but assert boundaries when I know she's had a drink. Because actually engaging with her is too frustrating for me.