Non-Compete with the Employer

Hi All, Please help me with the current situation. I am on a H1 B Visa and I have transferred my H1 to new employer x (To whom I was doing a sub contract thru middle vendor). Now my previous employer is against me saying that I have signed a contract with him when I have joined as per that I have to pay $20000 for liquidation damages. Below are the wordings from contract. Provide or attempt or provide, directly or indirectly, any services to any Clients of EMPLOYER. to which EMPLOYEE may be introduced or contacted during the Employment with EMPLOYER. Above the just one para and i have 5 more like this. I have following questions. 1) Legally is the above lines are valid or not 2) If I go legally still do I have pay the penality 3) Is it better to negotiate with the employer and sort it