> So. Let's say I have this dad. He has a sister named Jane. Jane marries this guy named Harold. Harold and Jane have two kids, Christina and Michael, my cousins. Then Harold and Jane get divorced. Is Harold still my uncle?
>
> -Eric Sleator
> Wed 3 Oct A.D. 2002

Technically I believe he is now better described as your aunt's ex-husband. "Ex-uncle" sounds rather silly, because the term covers uncles by blood as well as by marriage, and obviously it is not possible for a blood relation to become an ex-whatever. I still think it would be correct to address him as Uncle Harold, because this context relies more on your personal feelings than on semantics, but describing him to other people as your uncle might lead to confusion.

I grew up calling my father's first wife's brothers Uncle Len and Uncle Les, despite them being unrelated to me either by blood OR marriage, but if speaking of them to an outsider, I would not have called them "my uncles".