((((hugs)))) So sorry for you, it just plain stinks to see our kids make terrible choices. About all you can do is pray for them. Often family has the least impact when you try to help. What I do is pray God will bring the right people and circumstances into their life asap (even if that means hitting a bottom) so that they will be willing to change and accept responsibility for their choices. *sigh* no easy answers...
I work with a gal like that - she's got 3 kids by 3 different guys, too.