contract signed in india under duress

I am a teacher. I was made to sign a service contract and promisory note in India which stated that I have to pay an agency fee of $6,500 + attorney fees of $1000 in exchange for a job offer. I was never given a copy of the contract at that time. I came to the US and the job I was promised was not there. I got a temporary 3 month job as a teacher with no benifits and no paid holidays. The owner of the employment agency signed the contract here in Houston and added a line in his handwriting stating that the contract had been executed in Houston without my knowledge and without my initials on that line but he has put his initials on that.I refused to pay the agency fees,so he sued me along with 12 other teachers who were in the same situation as I was. He did send me the copy of the contract after suing me .The contract stated that the agency was just suppose to assist the teacher to get a job letter .He has sued us under his alias name and with a different signature.He did loose in small claim court against one of the teacher and then withdrew all his cases against rest of the teachers including me. Then he sued us gain in civil court.The contract also states that that all the disputes or claims shall be settled in accordance with the arbitration claue. Is there any way i can prove that the contract is not valid and was signed under duress.Can the same person use different signatures and aliases in a legal document.