I don't know if it is really a bad idea for a Therapist to also see a friend of yours then they can hear both sides of a conflict that may arise between the two of you. When I was in Junior High a friend of mine saw the same Therapist as me but that was probably because it was the school Therapist that we both saw.

The Husband situation may be a little different but I really see no harm in it (once again they can hear both sides of a conflict between the two of you).