You cannot “fix” your friends or relatives no matter how stupid a decision they make.

Not you if you just don't pick up the phone.

Just tell her that it's a bad idea, she's free to do what she wants, but when it turns out badly, you won't be sympathetic and won't want to hear about it. And, in fact, you can tell her the whole situation isn't something you want to discuss because it makes you uncomfortable. It's going to be a rough time for everyone involved for a while, though.

I’d be the one who ignores it and let’s her ruin her life

A thought: Don't take her calls or block her altogether.