"Ya Sudahlah" could be translated as "ah whatever".. but I dont think the sense is for the feeling of 'whatever'. For me, as an Indonesian :), it's more like "It's OK" or "It does not matter'.. and if want to say "whatever".. we mostly say "it's up to you" with a little bit sarcastic/negative tones... (just trying to explain small stuff, and please correct me if I made mistakes in translating 'na egal' as 'whatever'. My german is bad still ;) )
This song was pretty popular.. but I did not really like it.. because after that its gone already.. not phenomenal.. hehehe
but you did try to sing it I guess heheh