AITA? I've called my ex a prostitute in class bc he trying to hit on to 13 girls in that week. (Really situation)

Am I the asshole?

Today there was a March 8th celebration in class, and the teacher asked why Igor (my ex) was sad. He said he'd been rejected by 13 girls this week (I think he said this to make me jealous, since we broke up almost two weeks ago). I called him a prostitute, The whole class sided with me. Maybe I shouldn't have called him that? Am I the asshole?

PS. He initiated the breakup, and it was because I didn't give him "enough attention" (I didn't write to him for three days because I moved to another city and celebrated my mother's birthday).