Ex boyfriend

So me and my boyfriend broke up about a week ago, he's been going out and meeting his ex and the girl I was scared about him getting close to. The thing is is that I met a boy yesterday but now my ex is calling me a slag and that I can't resist dick and horrible things like that. I don't know what to do now. I really do still love him but I have feelings for another boy. I know I can't go back to him but it hurts when he's saying this to me. Advise please