Thank you. Can you please clarify this doubt to me?

If the answer is "since 1998" can the question be: How long is it since you got married"?
Is the sentence "How long ago did you marry"? wrong. The verb is "get married".
When did you divorce your fist wife?

1 answer

"How long have you been married?" <~~Yes, that's the best way to phrase the question.

The answers then could be any of these:

Since 1998.
Thirteen years.
A long time!

etc.