Cam employer force anyone to complete the 3 month notice period?

Hi, I have resigned from my present company stating i have family problems and i cannot continue the service and i want reliving in 1 month, for rest 2 months i am ready to pay the money, but my HR is forcing me to complete the notice period and also threatening me about extending the notice period. I have very small amount of work which can handover to other colleagues very easily in 1/2 weeks.But still they are forcing me to complete the notice period only to control the attrition rate for this year. Refer below para from the appointment letter- "Your appointment has been done after an extensive process for an important position which requires your skills and experience. This appointment may come to an end at the instance of either party by giving the other a notice in writing for three months. Your relieving from the services of the Company would be contingent upon successful serving of the full and complete notice period. Failing to do so would entitle the Company to recover damages for all losses caused due to any shortfall in serving of the full and complete notice period. The Company in addition to its rights to recover damages will not furnish a relieving letter in case of shortfall in the notice period unless such shortfall has been signed off by the appropriate person in the Company. In exceptional situations the Company reserves the right to waive off notice period at its sole discretion." What should i do in this case, please help me?