If I understand correctly, your ex is threatening to sue you in small claims court for damages to his UN-insured vehicle in an accident that occured in '09? Your bankruptcy, discharged in 04/11, only applies to legal debts incurred prior to the discharge of those debts. Since your ex has not prevailed in his threatened action against you there is no debt owed that could have been discharged by the bankruptcy proceedings.

My advice would be to let him carry on about his business if he should choose to do so. If he wants to file a lawsuit against you, respond to the summons. Then you can testify that you refused to participate in his "demand" to commit insurance fraud (so he could recoup his losses) and that it ended your relationship with him. He might not be so keen to have that information laid out for all the world to see in court.