Proverbs or Old Sayed Sawes bound with Lexicon Tetraglotton
Yes, there is "no point crying over spilt milk" because whatever happened has happened and there is no way to go back to the past to prevent the happening. However, crying over spilt milk is useful in that is helps us to feel regret and hence we will learn to prevent the happening in future.
I cried when my Mother swatted me for spilling my milk. Origins are most likely sprang from faery lore. It was thought, to attract faeries and their blessing or good luck to a house, laying out a "shrine" with food brought favour to the house. Whenever milk s spilled, it was considered the offering was discounted and wasting the food also added to the difficultly in feeding a family.