I'm so hurt

I just need to vent. I'm so hurt right now. I just found out that my fiancé was talking to his ex girlfriend telling her that he thinks about her a lot and he creeps on her facebook page and that he reminisces and dreams about what they had. I confronted him about it and he says that it didn't mean anything. Something like this isn't going to be easy for me to get over. I don't know what to do.