I think that if the emotional bond was there before you had a partner then it's more of a life long friendship than 'cheating'.
I have friends that I tell EVERYTHING to.. and one of them is an ex partner. Doesn't mean that I want anything more from this person than just to be there for me when I need (and vise a versa for him).
I don't think that the bond can just go away when you get into a replationship. Why should it either? Emotionally connections with people a hard to come by.

Is it that you think you are cheating or does your partner consider this bond you have with another cheating?