Whether the Will is cancelled or not, you are entitled to a legitimate share to the extent of 1/3rd share out of your father's 1/2 share in the property.
If your brother is constantly troubling and torturing you then you may issue a legal notice to both your mother and your brother to divide the property that was left behind by your deceased father and to allot your rightful share in the property with separate possession.
Subsequently you can fie a suit for partition on the same lines,.
This legal step may make them to come for an amicable and compromise settlement.