PLEASE HELP!!!!!

My EX suffers from Cerebral Palsy and is claiming that 3 years ago my 2.5 year old son kicked him in the head causing him to have a concussion and can NOT remember spanking my son, or shoving soap into his mouth, or slapping him across the face... I need help because I have been blamed because my EX says he can't remember because of the kick to his head by my toddler....