What do I say to this guy?

I said "Goodnight... I'll b dreaming of u dead & ill b celebrating ur death like Osama bin laden's." then he said "Good for u emo chick" "All I got from that was u dream of me <3 I think that's cute" "Bye bye have a beautiful time!" what do I say to this?? It can be however mean I don't care I'm never nie to him... He never leaves me alone... JUST HELP ME PLEASE!!! And by the way... I don't like him!!!!!!!!