Worst girlfriend he ever had

My boyfriend and I got in a fight and he told me “you’re the worse gf I ever had” his ex cheated on him and had sex with guys while dating him and we had a disagreement about his sister and it turned into something big and he said that to me. I don’t even talk to other guys and do so much for him. It hurt so bad now he’s saying he didn’t mean it which I know hes lying because how would his ex come to his head to say that? I’m really hurt and down. What would you do