If you don’t get your little girl away from her asap she will turn into mommy’s evil mini me.

You dont. This is toxic and a precursor to much worse. You protect the child and get them away from her.

Divorce her now. Get the kids as far away from her as possible, especially your son. She's abusive, manipulative and a cheater, and is already a rotten influence on your daughter. Whatever her issues are, waiting until she's dealt with them to finalize the divorce will only harm the kids in the long run. She needs to hit rock bottom before she'll change, and yes, there's a good chance she'll OD again and die, but you can't help her if she won't help herself. At this point the well being of your children is the most important thing.