Regretting some past sin that has already been forgiven?  You cannot change it!  You do not need to bear that!  Christ already has!  “He himself bore our sins in his body on the tree, so that we might die to sins and live for righteousness” (1 Peter 2:24a NIV).  You are forgiven.  Don’t go back there!  Surely, don’t dwell there.  Instead the Book is reminding us to die to all sin.  By grace, crucify them all.  They are past, so keep them that way.  Bury what is dead and move on.