why does it not exist?...why is it fictional?...because u say so?...what if i said the keyboard im typing on isnt real because i dont belive in them...does that make me right...
ur preception of time doesnt change the fact that it exist whether u want to belive it or not...time is a concept, a concept backed up by mathematical equasions, unless u have some proof toehr than, its fictional because it didnt exist untill humans discovered it...thats like saying...

fire didnt exist until humans discovered it...or even bacteria and what not didnt exist untill humans discovered them...just cause we didnt know about it doesnt mean it wasnt there....