Tell him "Please do not call me that anymore. We aren't together anymore."
If you're good with a cutting tone of voice you could ask "and your point is?"I get the feeling that if you ask him to stop he may not as he can see it's affecting you. I recommend asking him why after so many years he has decided to call you that. ( in a interested yet disinterested type of way ) Then tell him you think it's "silly" as that was so long ago.![]()