Hi Seeker,
I had a very similar situation when I got married four years ago. My husband had a female friend he had known since childhood with significant alcohol ans drug issues that we didn't invite to our wedding as she was highly volatile and would instigate fights and drama with people she didn't even know. It cost us our friendship with her but her behaviour was so often outrageous ( police being called) that we couldn't risk it. I have no regrets, it would have spoilt a beautiful day and I would not have relaxed with her there. Its not your fault your friend has alcohol issues an you are not responsible for her feelings. All the best xx