How to get over an ex

We broke up today and I am already having a really hard time coping. I already know that he's gonna be a jerk on social media and/or he will manipulate me into coming back. He is already talking to other girls and posting about them which sucks because I'm already so sad and insecure. I just don't know what to do or who to talk to. How can I move on? He's a really good looking man so many woman will probably get with him it just sucks :( please help