Marital Infidelity and Extent of Disclosure

I am a person who had an affair during my marriage.  I'm not looking for someone to cottle me or tell me it was alright to do so...it was inappropriate and immoral and I fully accept responsibility for my actions.  I do have a question however.  In the interrogatories I received from my STBX's attorney it asked if I had ever had an extra-marital relationship of any kind and more specifically asked for name, address and phone number of the person I had the affair with.  I've been told on more than one occasion that this person has a right to privacy and I'm not legally obligated to provide that specific information, only whether or not I engaged in an extra-marital relationship.  Does anyone have experience with this or know what I'm actually legally obligated to provide.