Establish boundaries.

 Always keep in mind that it is ok to say no to others.

Even if they will throw words at you for not doing what they want you to do, then explain to them why you refused. Remember that emotional blackmail is one way that they will be controlling you, so you better read the signs.

Work on your self-esteem. Some people may end up in codependent relationships because of low self-esteem. Then commit to yourself that you will work to improve it. Loving yourself more and trusting yourself more will give you the chance to gain the confidence that can possibly give you a more positive environment.
This way you can interact more with other people and you can feel that there are people who will accept you for who you are. · Free yourself from the other person. Even if you have already talked about it and see no changes from your partner, then it may be time that you cut the cords. No matter how you sacrifice, you can never change an unwilling person. Like you, the motivation to change should come from within and not from somebody else.
Changes are more effective if the urge to change is from you. · Be firm. If you have decided to walk out, then there should never be a chance of you thinking to walk back in. Good if you have a cooperative partner, you can both help each other out.
However, if your manipulative partner (or whoever) gives you the drama, the physical, verbal and emotional abuse just to keep you, be firm to stand what you have decided on. It will not be easy as you are used to having this person around.
– Shahida Arabi.