i assaulted my roommate and the police were involved, he refused to press charges and i wasn't arrested. The next day he told my boyfriend t...

Question

i assaulted my roommate and the police were involved, he refused to press charges and i wasn't arrested. The next day he told my boyfriend that if i didn't pay his "medical bill" he would press charges

Answer

What is your question? If it is "Can he now tell the police that he has changed his mind and would like them to prosecute you for this crime?", the answer is Yes.