It seems like a very sensible idea. You are family, and are allowed to express your concerns.

Unfortunately, there's only so much you can do.

People have to make their own choices. That's just the way it is. I'm sure you wouldn't let a family member or friend make decisions about your life, or who you married, or what your hobbies are etc.

I'm really sympathetic. It must drive you crazy, having this odd woman influencing him so strongly.

But, as i said, it's his life.

BTW my instinct about her is that she is an alcoholic.

I guess you'll just have to stay as emotionally detached as you can, so that this doesn't take over your own life, and be there to pick up the pieces when things go wrong.