Get your hands on a copy of "Codependent No More" by Melody Beattie, and see if you see yourself in any of that book.
Read the stickies at the top of this forum. Educate yourself on addiction.
Get yourself into some professional counseling (preferably someone who has experience with addiction and the family dynamics).
Find out if you have Alanon or Naranon in your area. Face-to-face meetings with others who have loved an addict can be a tremendous source of help.
As has already been said, those children have no choice in how they live, and they need one sane and emotionally stable parent.
You didn't cause her addiction.
You can't control her addiction.
You can't cure her addiction.
I hope you continue to post and please know that you are among friends.
:ghug2 :ghug2