Diane M. Horstmann

Diane M. Horstmann, born August 23, 1951, passed away peacefully on March 18, 2026. Her life was one marked by devotion to family, faith, and community.

Diane’s early years were shaped by her education at St. Jerome Catholic Grade School and Rosary Catholic High School, foundations that nurtured her strong spiritual beliefs and commitment to the Catholic faith. She was an active member of the Assumption of the Blessed Virgin Mary Catholic Church in O'Fallon, Missouri, where her faith was a cornerstone of her daily life.

Diane found joy and fulfillment in creative pursuits, especially in crafting wreaths. These handcrafted wreaths held a special significance for her, symbolizing love and togetherness, cherished by her family and grandchildren.

Diane’s legacy lives on through her loving family. She is survived by her devoted husband, Glenn Horstmann; three sons, Steve (Theresa) Horstmann, Tim (Heather) Horstmann, and Chris (Rebecca) Horstmann; and her treasured grandchildren Jacob Horstmann, Graham Horstmann, Kennedy Horstmann, and Abigail Horstmann. Diane was also surrounded by many other family members and friends who hold her memory dear.

She was preceded in death by her beloved grandchild, Sebastian Horstmann; her mother, Dorothy A. Aubuchon; and her father, Leonard H. Aubuchon.

Visitation to honor Diane’s life will be held on March 27, 2026, from 9:30 a.m. to 10:30 a.m. at Assumption of the Blessed Virgin Mary Catholic Church, located at 403 North Main Street, O'Fallon, Missouri. This will be followed by a Mass of Christian Burial from 10:30 a.m. to 11:30 a.m. A graveside service will take place at the same location starting at 11:30 a.m.

Memorial contributions in Diane's name may be made to Assumption of the Blessed Virgin Mary Catholic Church.

Diane M. Horstmann’s life was a testament to love, faith, and creativity. She will be deeply missed by all who knew her, yet her spirit will continue to inspire through the love she shared and the memories she created.