Put your past in the past

How now, my lord!

Why do you keep alone,
Of sorriest fancies your companions making,
Using those thoughts which should indeed have died
With them they think on?

Things without all remedy
Should be without regard: what’s done is done.

–Lady Macbeth to her husband
(and a million wives since,
to a million regretful husbands)

Shakespeare’s Macbeth
Act III, Scene 2