Is diet soda safe...do u drink it?

i read diet soda is sweetened with aspartame which not only does cause cancer but it also can kill you instantly or it can make you blind all of a sudden if something goes wrong in your stomach cuz aspartame contains a small amount of methanol which can make u blind or kill u. for example pilots cant eat anything with aspartame cuz they cud suddenly become blind or die and the plane wud crash