We don’t know at what point Jacob delivered his message on this apparently notable occasion, but we know that there was a lot of doctrine being taught. They are at the temple (Jacob 1:17). Families are present. The Spirit is present. It is the type of setting where someone’s heart can be touched when the prophet stands up and lovingly but sternly testifies of the peoples’ sins. Jacob no doubt expressed a lot of love to them prior to this. It is clear, from his anxiety for his people, that he was truly a caring person. I’m sure he was beloved by the people, and so their hearts were likely in the very best possible place to receive his instruction.
I understand that many women, when they have been in some way betrayed by their husbands, tend to place the blame themselves. They wrongly think they have done something wrong, and that it is all their fault. So to hear someone like Jacob saying "this is not your fault at all" must have been very consoling. Church leaders today say this same kind of thing all the time, and for good reason. Thus, while Jacob’s message was painful to both husbands and wives and children, he did his best to console their wounded hearts.
Jeffrey R. Holland, "Place No More for the Enemy of My Soul," Ensign, May 2010, online at churchofjesuschrist.org.