My younger brother who had been struggling with drug/alcohol addiction for years. After watching my mother carry him into the house when she found him passed out behind the garbage cans in her garage (for the 4th time) I decided I'd had enough.
The next day I sat down with him and told him that I couldn't watch him hurt my parents any more. I couldn't watch him hurt himself. I couldn't watch him kill himself. I told him I would always love him, and should he ever decide he truly wanted help, I would be right by his side and give him whatever I could, but until that day I wouldn't have him in my life.
That was the last conversation I had with him. He died of an overdose a little over a year later at 25 years old.