Firstly, you should communicate with your wife and make her understand that whatever she is doing will affect your child. It will ruin her life and she will not be able to handle this. It would be great if your wife understands and bring changes. But if she still continues to do drugs then you can take legal action. You can file a case against your wife and take this matter to the court for the children’s protection and security. You can demand to get your child’s custody as she is not safe and secure with her mother because of her drug addiction.