What should i do ?

I had sex with a guy and he ghost me ofcourse, i learned my lesson though for giving it up too early, but idk how to handle it or get him out my head.. i goto parties and i see him messing with other girls ☹️ also i tell myself that his dick is little and that i could find somebody with a bigger inch and that would also do more sex positions than just one 🙄 but it doesn’t help.