Walk away right now. 4 months is a loss of time... you don't need to make it 6 months or worse yet, a year of pain and deception.
He's calling you names because he's been found out-- he's verbally abusing you to cover for the fact that he's being faced with consequences. You did the right thing absolutely-- his family needs to know. How he reacts is how he reacts, don't let it sink in and hurt you.