I have Blocked my Mother's Phone Calls

http://counsellingresource.com/ask-the-psychologist/2009/02/02/controlling-manipulative-mother/

• Dealing with a controller/manipulator is like being arrested — everything you say can and will be used against you! If you reduce information provided to your mother to grocery-store level, which I recommend — such as the weather, school activities of the children, etc. — she will encourage your sister to pump you for information. To manage this situation, you must control the information presented to all family members, perhaps saving your private information for your non-family best friend.
• Assume that any time you challenge your mother, you will be punished in some manner. Her punishment can be verbal confrontation, the silent treatment, increasing her activities with your sister’s family, or being excluded. Remember that while men are prone to physical aggression, women are prone to “relational aggression” — using relationship features to punish or attack others by alienation, spreading rumors, exclusion, etc. She is mostly concerned with her feelings and for that reason, will intentionally justify doing something she knows will hurt your feelings.
• Your mother will be threatened and jealous if you and your sister have a good relationship. If you and your sister decide to do something as sisters, without your mother, one of you will be punished. Controllers demand to be the center of attention and when that doesn’t happen, they retaliate.
• Having a controlling parent is rather toxic to our self-esteem and self-worth, as you mention. If you are slowly developing self-confidence, your sister may not be able to help you break away. She may still be focusing on keeping Mother happy. You’ll need to break away on your own and for this reason, professional counseling may be helpful. I’d recommend reading my introduction to personality disorders on this website as well as reading related questions by selecting this topic from the list of popular topics in the sidebar of the page. Millions of healthy adults must deal with a controlling and/or manipulative parent or relative.
• Your mother behaves in a way that is to her benefit, as you describe. For this reason, you may need to accept the fact that as you become more healthy and independent, she will have less contact with your children and family. She will go where her selfish needs are met and where she has more control. Redesign your family to include other healthy families and their children. In life, we have the family we are given…and we have the family we create from those around us.