I Miss My Ex-girlfriend

Its been over 7 months since my ex and me broke up. Time to time i miss her dearly,even thou shes in a relationship now. She unblocked me a month ago on FB yet blocked me again. We haven't made contact in so long. I know should move on but,its hard when shes in my head. We only been dating for 4 months yet,i felt i knew her my whole life.