Your past to your future

They say to watch what you do b/c the past will come back an haunt you,
well what can one do when there past is exactly what it is their past,
ones mistakes are are never forgotten,
but surly edited by all those around them,
how do you save your self and your relationships,
when your past is brought up,
people spread shit,
and you boyfriend, friends and family don't believe you,..
you change who you are in hopes of changing who you once were,
you know that you've changed but no one believes you,
how do you forget your past and make your future,
and if you make your future how long will it take others to lose your past and think of who you are now?