Just don't make discussions "personal." Don't pretend to reply to a quoted item and then start making your discussion about something else entirely while being inspired by other discussions the person may have had with you that have nothing to do with what you're talking about.
That's just "wrong." I don't care if you disagree with something I wrote, but if you're against "me" as a person and as some holistic entity you have constructed due to your interpretations of other things I have written then I don't want to engage in a discussion that includes such a thing.