Brothers and sisters, I do not consider myself yet to have taken hold of it. But one thing I do: Forgetting what is behind and straining toward what is ahead,  I press on toward the goal to win the prize for which God has called me heavenward in Christ Jesus.
(Philippians 3:13-14)

I think this scripture lets us know that, although we have made many mistakes in our lives, it is never too late to begin again, to head in the right direction.  We can't undo the past but it's one of the best learning tools made available to us.  So keep going forward, toward God and His everlasting promises.