[David O. McKay]
... Brother 'J' is right in classifying adultery as a heinous sin, but he is wrong in saying that 'a person can never repent of this, and that he or she cannot undo this sin.' See Doctrine and Covenants, section 42.
The sister to whom you refer should not worry. If she has truly repented she will not be separated from her children and husband. Brother 'J' is probably guided in his assumption by an alleged remark printed in the Compendium, page 280, but this alleged saying of the Prophet must not be construed to contradict the revelations of the Lord.
[David O. McKay, Letter to Mrs. Henry Price, as quoted in Minutes of the Apostles of The Church of Jesus Christ of Latter-day Saints, 1910-1951, Privately Published, Salt Lake City, Utah 2010]