Completely forget about a guy and move on.......?

Ok so i wasn't thinkin about my ex at all up until abut 3 days ago when i found out hes got a new gf and im jealous but not jealous at the same time..like i can get him outta head and the song "When it was me-Paula DeAnda" keeps playin in my head and i keep singing the lyrics "you said nothing felt as good as when u gazed into my eyes and now you dont care im alive how did we let the fire die" & "and im not jealous no im not i just want everything shes got" & "nothing about me has changed thats why im here wonderin wat makes her so much better than me?"...those lines keep playing over and over again in my head and i cant stop thinkin about him and i wanna kno what can i do to keep myself from thinkin about him and basically forget his *** cuz its driving me crazy and i just wanna forget bout him and his gf..so help please?