Save every message he sends you!!!!
Do not respond to him in anyway!! Call an attorney and ask for a reference to an attorney familiar with equine law. Don't post any more case specific information on this forum about him or this deal. No one here can help you stop this guy from railroading you into court for what appears to be a fraudulent transaction. When you file your counter charge be sure to file for court costs as well.
Get Professional Help Now!!