In Montreal, Lafontaine was educated at the School of the Bon Pasteur, and at the Convent of the Sisters of the Sacred Heart, St. Vincent de Paul. She was one of the vice presidents on the formation of the National Council of Women of Canada and was honorary vice president of the Victorian Order of Nurses.
In 1861, Lafontaine first met her future husband, Sir Wilfrid Laurier, at the home of Dr. Séraphin Gauthier, where both were boarding. During this time she was a piano teacher to Gauthier's children.[4][6]
On May 13, 1868, the two were married in the Saint-Jacques Cathedral.[6] The couple lived at Arthabaskaville until they moved to Ottawa in 1896. Ultimately, their union was childless, to Laurier's dismay.
Lafontaine was one of the vice presidents on the formation of the National Council of Women and was honorary vice president of the Victorian Order of Nurses.[7]
On 17 February 1919, Laurier died. Lafontaine outlived her husband by more than two years. She died in Ottawa on November 1, 1921, at the age of 80.[5]