Early 2000's story, about 20 pages maybe in a larger scifi compilation. The stories were donated for a charity - an Asian relief fund. They were from well-published authors.
An approaching storm, an elderly retired mirror maker and widower was out gardening. Used to be a rough guy and gambler who drove his wife nuts. A woman commissioned him to make a custom mirror. He fusses and tries to sell her something he had tucked away but eventually agrees to make the mirror. When he's silvering the glass he gets dizzy, keeps thinking he's going senile, but the mirror finishes fine.
The new mirror had no reflection at all, just black. But the lady takes it. To "pay" him she tells him to look in the mirror and he gets sent back to an old horse race, then blacks out in disbelief.
When he snaps to he's back in his living room and his life has been changed - his wife had somehow not died.