Why is my ex calling and texting me just to tell me im ugly?

He keeps calling and texting me insults and I haven't done anything to him. He's also been calling me and hanging up when I answer then texts me insults. Also, he called me last night again after I stopped talking 2 him in text and called me saying I'm ugly and some other crapp.He broke it off so idk why. I am over him I just don't know why he's behaving like this, I admit I've been nonchlant towards him , and even with his insults because I am over him. He also texed me saying "hahaha your a weirdo" what is his problem