Adjusting a contract between 2 people only signed by those people, no witnesses.

I am a lawyer in CT and practice in this area of the law.  A contract that is enforceable where there is a meeting of the minds as to the terms.  if you and your ex did not truely have a meeting of the minds then the contract may be voided.  You may also claim that your ex misrepresented information to you that amounts to fraud and she took advantage of you.  In any event, i suggest that you try to work this out to avoid going to court.  However, a small claims judge may enforce the contract on the grounds that you did not read it carefully.  I suggest trying to work it out. otherwise, file a small claim suit alleging that your ex defrauded you and or misrepresented information to you and the contract is unfair.