You told me you teach English.

[nelson13]

A and B talking.

A: You told me you teach English in a rehabilitation house.

I hope to know if B treats it as a question, how should he answer it?:

Yes, I did. (=I told you so.)

OR

Yes, I do. (=I teach English.)

[Raymott]

A and B talking.

A: You told me you teach English in a rehabilitation house.

I hope to know if B treats it as a question, how should he answer it?:

Yes, I did. (=I told you so.)

OR

Yes, I do. (=I teach English.)

He'll answer in it the way that conveys his meaning - as you have indicated.
He might also just say "Yes?" and wait for you to make your point.