He was embarrassed that he had to disclose these abominations before the families of those who were guilty because their feelings were tender and chaste. It is obvious from this verse that Jacob was going to disclose what some of these men had been doing secretly and therefore it would come as a great shock to many of their wives and children.
Jacob knew that the women and children had come to this conference expecting to hear the pleasing word of God. They had come to be inspired and renewed in their souls. That was why it was particularly painful to him to have to fulfill the strict commandment of God and use the time of this conference to admonish these men for their crimes. Jacob said that what he had to disclose would not console the women and children who had come to be spiritually fed, but his words would be like daggers which would pierce their souls and wound their delicate minds. Note the eloquence of Jacob. His style of forceful expression is quite different from the rather simple and direct style of expression used by Nephi.