what is done cannot be undone

what is done cannot be undone AND what has been done cannot be undone () — сделанного не воротишь; что сделано, то сделано

Also found in the terser, more casual form what's done is done.

Example 1: I hope you will think twice about it. Second thoughts are best. What's done cannot be undone. (S. Ferrier, Marriage III. xxi.)

Example 2: What's done is done‥. I'll see you don't suffer for it. (H. Harrison, Technicolor Time Machine )

Example 3: ‘And although I am very, very sorry I involved you in this, Ariel, what has been done cannot be undone.’ (K. Neville, Magic Circle)

Related vocabulary:
[сделанного не воротишь]
[you can't unring a bell]
[let the genie out of the bottle]

сf.:
[слово не воробей — вылетит не поймаешь]
что написано пером, не вырубишь топором