The Rebbe acknowledges the letter and mentions having prayed on the Rebbe Rayatz’s Ohel for the writer and his family. He emphasizes the great merit in promoting taharat ha-mishpacha, noting the Previous Rebbe’s mesirus nefesh for this cause. The Rebbe expresses hope for clear improvement in this area, both physically and spiritually.
https://www.torahrecordings.com/rebbe/igroskodesh/015/010/5561