From the Globe and Mail:
Despite her great success, it is known that she suffered from depression, that she was isolated, sad and filled with worry and dread for much of her life. But our family has never spoken publicly about the extent of her illness.
What has never been revealed is that L.M. Montgomery took her own life at the age of 67 through a drug overdose.
I wasn't told the details of what happened, and I never saw the note she left, but I do know that it asked for forgiveness.